I would heavily not recommend getting secondhand GPUs for at least a few years, as in pretty sure the market is still flooded with crypto miner refuse. Basically they get a new gpu, overclock it and run it into the ground then sell it secondhand. Getting a crappier gpu is better than taking that risk, and you can still get refurbs and the like through main retailers. Because if those are broken you can at least get a refund or replacement.