Looking at eBay listings, lots of used Hackintoshes are offered, but very few are sold.
If OP wanted to successfully sell his computer, he would have to put Windows on it before offering it on eBay. And even then, I don’t think he’d get much more for it than the price of the Windows license.
On the other hand, had OP spent his $800 on a Mac mini, he would be able to sell it for close to retail price. Even after a year, he could easily resell that computer for $600.
Used Apple products do hold their value better than anything - personally I think people pay way too much for used Apple gear, but hey, they have their high-end niche and people are willing to pay for it.
But to say that selling his computer would net him little more than the Windows license is absurd. It wouldn't be Apple resale prices, but he should definitely be able to get %50 back. He'd get the most value by parting out the system.
So what you’re saying is that, of the $850, he’d be able to recoup $425, as long he’s willing to take the computer apart, put all the components back in their boxes (assuming he kept those), listing all the components as separate ads (writing descriptions, taking pictures), communicating with all the buyers and sending out a dozen packages to separate addresses? They will easily take 20 hours. Unless his time is worth less than $22 per hour, he’d be losing money by selling the computer as parts.
If OP wanted to successfully sell his computer, he would have to put Windows on it before offering it on eBay. And even then, I don’t think he’d get much more for it than the price of the Windows license.
On the other hand, had OP spent his $800 on a Mac mini, he would be able to sell it for close to retail price. Even after a year, he could easily resell that computer for $600.