He is talking prices for second hand I'm fairly sure. Its possible, I have seen prices that low but not many of them, maybe he just knows a repair shop or something. The alternative is they arent fully tested which is risky.
What is the point of buying AMD cards? You are quite limited, ETH and Monero mining mostly.
and equihash coins - ZCL, ZEC, ZEN, BTG, HUSH, KMD.
And cryptonight coins - XMR and ETN being the most prevalent.
And ethereum coins - PIRL, ELLA, ETH, ETC, MUSIC, UBIQ, EXP. Not to mention the dual mining for SIA, DECRED, etc.
You can also mine the NeoScrypt, Pascal, and Skunkhash based coins as well.
Its not as limited as one may think. and the equihash are quite profitable right now. But I do agree NVidia > AMD for options/flexibility. I run a mix of 50/50 right now but that is due to card availability.
Skunk is very easy to mine and tune for, likes a higher core speed and is ideal for anyone who is mining and actually also using the card in a system. Just needs core temp below 70c generally