Shoes. I have a weakness for high quality men's shoes, Allen Edmonds to be exact. One of the few shoes still made 'old school' by hand in America.
As long as it's not an obsessive collection (like a floor-to-ceiling rotating shoe rack in your 500 sq ft mahogany walk in closet) I'd say high quality shoes are actually mustachian.
Allen Edmonds shoes will last a lifetime. Sure, the upfront cost is $300 or so. But if you rotate them, clean & store them properly, and resole them every several years you'll come out way ahead in the long run vs buying a $100 pair every couple of yrs. Can't remember exactly, but I think Jacob of ERE has a $300 pair of leather shoes that he takes really good care of.
To be honest, I don't agree with the buy it for life mentality for anything that is worn. Fashion changes so much that anything you buy will go out of fashion if it's around long enough. Styles are touted as timeless, but it doesn't make the cut in reality.
For me, fashion certainly changes so I have an ever changing sort of minimal (& super low cost or free: read castoffs) wardrobe. But I understand that is not the case for many
For clothes, I don't buy 'for life', but definitely 'for longevity'. I don't expect my winter boots to last forever, but I live in Quebec, in the country, and it gets Really Effing Cold November-April. I don't mind spending 150$ for boots that'll keep my feet warm for 6-7 years... (Recommendation: Sorrel, or, if you find them used, Pajar... Not the new Pajar though, they changed their manufacturing and suck hard).
For anything 'basic' (black work pants, white dress shirt, large leather tote, etc), you can assume fashion isn't going to change that quickly, and it's worth buying quality and hand-washing. My white dress shirts (2 of them) have been in the closet rotation for 5 years now, excluding the 6 months of pregnant belly not fitting. Anything 'fashion' (non-classic dresses, patterned pants, jeans in 'this season's cut', that sort of thing) can be bought for pretty cheap... Personally I'm a fan of on-sale Old Navy (because for some reason their cut fits my body type super well if I size down) mixed quality basics (shoes, bags, etc). Today, for example, I'm wearing a good-quality dress shirt (5 years old, looks new, worn at least once every 2 weeks in that time, and originally 50$), black Old Navy pants (12$, fit fine), and cute boots ($$, but bought 5 years ago and worn at least 2-3 times/week from September to May for 5 years, and I still have people stopping me on the street asking me where I got them). Add a handbag (bought in Italy as a souvenir for 150$ on my last trip there 4 years ago and carried every day since... and it still looks pretty much new) and a scarf... Done. There are individual pieces that were $$$, sure, but the key, for me, is that ALL of these wind up being less than 0.50$/wear, even the super-expensive boots and pricy leather bag.
Obviously, YMMV on the worth of that. I'm the kind of lady who wears make-up every day, and the last piece of clothing I wore out (badly enough that the cobbler couldn't fix them for the 3rd time...) was a pair of red slingback heels. Aesthetics MATTER to me (for fashion, but also living in a good-looking house and doing things like plating my food well so that it's aesthetically pleasing...) There are ways to shift a MINOR amount of money into aesthetics for a relatively major impact... It takes time and effort and planning, sure, but it's not necessarily huge amounts of money!
