Thanks to everyone who's responded so far. I'm learning a lot! I'll take it from the bottom up...
@thefinancialstudent - You're right, I undoubtedly do have some unaccounted-for expenses, although I've tried to account for them here as best I can. The problem is that I haven't been in the habit of tracking my spending; I just try to make sure I'm saving enough. Obviously this is something I need to start doing and I'd love to hear any recommendations people have for budgeting/tracking tools (I take it a lot of people on this forum use YNAB).
I added one big expense I forgot to include originally, which is my $50/month insurance premium. The other expenses you mention are basically nonexistent in my life (see below).
@Dimitri, @RexualChocolate - Indeed, I don't own enough gold to take delivery and the custody fees add up over time. I'll take a look at options for converting to physical. I don't really want to have a debate about the virtues of owning gold; the thought of the Internet Archive burning up its servers to preserve yet another gold-related flame war kinda makes me want to cry. Suffice it to say that I don't think of it as an investment, but rather as an insurance policy. And yes, I believe the chance of a U.S. default or sudden dollar devaluation is very low. But I have some Russian friends who lived through the collapse of the ruble in the 1990's, and once you experience that, or even hear a few stories, insurance starts to sound like a very good idea.
@Spondulix - I'm not opposed to credit cards, just a habitual avoider of credit/debt. I will look into this too... please share specific recommendations if you have them.
@merula - Thanks, this is a reassuring set of calculations. I'm not quite ready to quit yet, though. I actually like my job, I just don't want to do it forever.
@dandarc, @rpr - Excellent, this really helps my understanding of the tax situation. I don't think I'm going to get a 630% raise anytime soon, but it's a good reason to try to do better in terms of pay. My current paycheck will in fact cover the deferrals of $18k+$18k and then some, I just won't have quite enough left over to cover expenses. I'm curious if anyone has experience with the strategy I mentioned in my original post, i.e. meeting expenses out of savings/investments while maxing contributions on a relatively small salary.
@humbleMouse, @EconDiva - I'll gladly trade frugality tips for financial advice! I feel embarrassed doing so, though, because it basically all boils down to being as boring as humanly possible. Frugality has become so integrated into how I live that it's hard to know where to start, so I'll just give a smattering and let folks ask about anything they find especially interesting.
*Transportation*
I've never owned a car - I walk, bike or take the bus everywhere. (I've been told this is inconvenient. I guess I just don't notice because I've never lived any other way.) When I travel, which is maybe twice per year, I take buses and trains; I haven't been on a plane in years. I live less than two miles from my place of work and walk to work most days. One of the perks of my job is that I get unlimited free bus rides with my employee ID card, and I rely on this quite a bit. Transportation costs will undoubtedly go up after retirement, but I'm not sure how to model this at the moment.
*Communication / Entertainment*
Here I rely on the four most powerful words in the English language: "I don't need it." No phone, TV/cable, or home internet. I borrow huge numbers of books, CDs, and DVDs from the local libraries, all for free. My main leisure occupations are reading and listening to & playing music.
*Food*
My motto is "eat low on the food chain and high on the supply chain." I buy in bulk and make everything from scratch, relying on a judicious combination of gardening, foraging and dumpster diving to obtain a significant portion of my food for free.
When making bulk purchases I often go through my co-op, but I also make an effort to seek out local business owners who are usually quite happy to sell me a sack or two of something at an even better price. For example, I buy green coffee in bulk (twice per year, from a local roaster) and roast it every week. All the roaster needs to do is take some coffee out of large bag, put it into a small one and charge me 20% markup, which is still way below retail - a win-win. I enjoy two cups of freshly roasted coffee every day at an average cost of $0.33 per day. (You don't need any special equipment to roast coffee, by the way - I do it in a saucepan on the stovetop.)
Instead of treating myself to fresh croissants at $3.00 each, I learned how to make my own croissants for about $0.30 worth of ingredients. Instead of buying expensive commercial nuts I gather the local black walnuts and hickories - which most people consider a nuisance - crack them out, and use them in my cooking. Around here black walnuts retail for about $16 per pound, but I get them for free. The shells can also be burned for fuel (they have roughly the same BTUs per kg as seasoned oak, and will work in a pellet stove). I gather apples, pears, apricots, and various berries from trees/bushes on public (and, with permission, private) property and make jams, jellies, preserves, applesauce, pies etc., all of which gets canned or frozen for winter use. I press apple juice and make hard cider, which I bottle in champagne bottles scrounged from the recycling bins behind downtown bars. I harvest a lot of common spring and summer greens (like nettles and lambsquarters) instead of buying leafy produce.
Because I don't have the space for a large garden, in the fall I usually do a couple of bulk orders for winter veggies through a local farmer who will sell me a bushel of anything for $12-$16. A bushel of rutabagas costs $12 and weighs about 60 lbs. I store cabbages, rutabagas, turnips, beets, onions, squash etc. in an unheated entryway which is my "root cellar."
Dumpster food: I try not to rely on it too much since it's mostly junk I wouldn't eat normally. There are exceptions though, like finding 40 lbs. of organic Peruvian bananas that got tossed in the compost bin behind Whole Foods because the staff thought they were a little too brown. I'm still going through those six months later.
When I go to the grocery store I always shop twice: First in the garbage, then in the store for anything I didn't find out back. It's best to focus on stores that are too small to have a trash compactor. Even if you avoid processed foods this can replace a significant portion of your food bill. For example, butter and cooking oil are expensive, but butcher scraps are easy to collect and render into lard, which freezes well and is surprisingly good for you.
I do a lot of sourdough bread baking and make my own yogurt, kefir, tempeh and miso, soft drinks, fermented veggies, etc. You can save a shocking amount of money this way and it's a lot of fun to do. The only caveat is that it's time-consuming. If you have a busy schedule, high-powered career, kids, etc. then maybe it's not for you.
*Clothing & Durable Goods*
When it comes to these items I do most of my shopping in the trash. Our society is unbelievably wasteful, and college towns doubly so. The students will throw out anything they don't feel like moving at the end of the semester. There's a particular weekend in August when people actually come from across the state just to dig through our city's trash, but good pickings can be had year-round. I've found everything from nice clothes to kitchenware, household appliances, computers, exercise equipment, office supplies, miscellaneous electronics, and on and on. Last summer I found a $400 racket-stringing machine. Whatever I can't use I sell on Craigslist or Ebay. I find a lot of easily repairable electronics which I fix up and sell - recently I found a professional blender that must have cost $1,000 new. The university itself is even more wasteful, although much of the waste comes in forms I can't use (like wonderful old architectural salvage, which mostly gets landfilled).
I'm disturbed by all this waste, but figure I might as well make use of it. Lately I've gotten more systematic about my scrounging and now use GIS software to keep track of the complex spatio-temporal relationship between the academic calendar, major apartment complex move-out dates and the city trash collection schedule. But I'm limited by the lack of a vehicle for transporting my finds, as well as a place to store large salvaged items. If I had these I could probably quit my job and just dive dumpsters for a living. Which sounds like a lot of fun, actually.
Ok, I guess that's plenty for now...