Whenever I eat out at work (about 9-10 times per month), I put $5 in a jar. Occasionally I'll use some of the money to pay for random stuff (like a coworker's kid's fundraiser) but last year I ended up with slightly under $500. I use that for computer upgrades on top of selling old components.
I am confused by this strategy. It rewards you for eating out, which would mean the more times you eat out a month, the more times you put away $5. Shouldn't it be the opposite -- every time you don't eat out at work, you put away $5 since bringing home food is cheaper than eating out?
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For the OP,
I haven't paid for a GPU since HD4890 days. Every NV/AMD GPU has been purchased with Bitcoin, euthereum, etc. I also resell older GPUs on top of this strategy. Technically, my 7970s earned enough bitcoin on their own to never pay for any GPUs over the lifetime but I decided to use that money towards other things instead.
Before mining, I used to buy GPUs with cash/pay off credit card by the due date and resold older GPUs. I try not to keep any older PC parts other than the case, mechanical drives, PSUs and monitors since the resale value on those tends to be rather poor (my experience); and yet for me these components last the longest.