ha! I came in this thread only to suggest winemaking! It's really quite frugal after the initial purchase of carboys (less than $100). I gather all my fruit for free by foraging local trees and bushes (and agreements with landowners...let me have the fruit, i'll let you have some wine in return). Mulberries, raspberries, apples, pears, jalapenos, sour cherries, rhubarb, peaches. I get all my bottles for 6 cents each at the local return center and reuse indefinitely. 50 cents for cork, label, chemicals. 50 cents for sugar to raise ABV.
Bam. $1 a bottle that is equal to $15/bottle wine. Even if you made 200 bottles a year (!) that's a <$250 investment for $3000 return/gifts credit/drunken enjoyment, etc...
Now, if you spend $179 on a kit wine, buy and toss your bottles, slap $1 labels on them...well, yeah.
Hell, even with kit wine, we've gotten good results that work out to about 3$/bottle. Considering that the absolute cheapest wine you can get around here is 9$/bottle (yay quebec)...
Someone mentioned woodworking as expensive, and it can totally be (if you do it like my dad does, omfg), but if you do it like we do... Capital investment of less than 500$ (or access to FIL's workshop in the shed,ya for living next to in-laws), and (very) basic skills (and maybe plans from a site like Ana White), and, this month, we're building bookshelves for the baby's room for less than 1/2 the price IKEA charges for cheap pressed wood and veneer equivalent. And a dollhouse for the toddler, since we can't find anything we like for under 200$CAD, dolls and furniture not included in that price. So... It certainly saves US money. Depends on the approach, I guess.
Um... "Cheap/expensive" is garage sales/kijiji-ing. Cheap because as long as you care about decor and house stuff it's a great way to achieve results for cheap. Expensive in that it involves spending $ as a default (unless you start reselling, which is not practical in our area.) I'm happy with the amount we spend and VERY pleased with the results, so I'm not gonna whine too loud, though.
Reading is cheap/affordable: mostly library books, and books I want to own are bought off Abe books at fairly low prices.
Cooking... I mean, if you're getting super-foodie about it then it won't be cheap, but mostly cooking means we can get excellent food on a cheap-ish budget (tonight: roast duck with grilled pears and brandy, accompanied by roasted squash and celeriac purée, probably followed by apple pie and ice cream. Total cost for us and 3 dinner guests: 18$, including the wine.) Find me another way to feed 5 people food that good for under 20$...
Gardening: affordable if you use free plants and/or grow veggies and herbs.
Sewing... Kinda like woodworking in that in can be expensive or affordable depending on your approach.