Resale value on the GPUs is also worth monitoring. While it remains high enough, you can discount much of the capital cost because you'll get a high fraction back if you decide to sell the cards.
Miners don't want to push their GPU's that hard, a hardcore gamer may overvolt their card to get a more stable overclock but a miner will undervolt it to run it cooler and increase the life of the card.
I'd rather buy a used Fury X off a miner than a gamer.