They are brand new, burned second hand you can get for 1000.
that is fine to buy used equipment, cars, vga cards, cpus and etc. people used to do it for a long time.
a lot people bought used ASICs after proper diagnostics and they worked as intended.
sure there is more risk against new equipment but the price 2-4 times less and that is totally fine reward for the risk, imho.
based on fact that profit is reducing very fast, purchasing used equipment may allow to ROI faster.