I think that for outdoor gear there is a meaningful correlation between what you pay and what you get - at least to a certain limit. Durability is one thing, but how well the gear actually works is also an important factor - it's outdoor gear, after all. I have consistently bought the high-end-shit, most of my outdoor clothing comes from brands like Arc'teryx, Icebreaker (wool), Scarpa (hiking boots) and probably a few others. For the milage I get out of it and how well it serves me I frankly don't care too much about the cost, but on the rare occation I actually need to replace something, I try to source it as cheap as possible of course. And I'm very picky on running shoes for obvious reasons, but I always buy last year's models at less than half the price.
I bought my shell jacket and pants in 2006 and I replaced the jacket last year. The pants are still going strong and will probably last another decade bar some unforeseen accident. In my opinion, good stuff in this department is worth paying for. Its not fun to be cold and wet when you could be warm and dry instead. Backpacks, tents, sleeping bags etc - I always go for the high-end stuff. It lasts so long the cost per year becomes rather irrelevant.
For pretty much everything else I don't really care what it is. I buy cheapish stuff on sale and wear it until it's well worn out. I also don't wash my sports/outdoor gear very often - that also greatly increases the lifetime. I don't really see the point in washing a pair of shorts or a running shirt after one trip - the next time they're used they will be all sweaty after a few minutes anyway.
I can barely remember the last time I bought everyday clothing for myself - that's a rare occation.