The used market like Craigslist and FB, plus other selling sites rigs are starting to appear. The asking price is stupidly high and I see many relisted a few days later. Just saw someone asking $4500 for a 6 gpu rx 580. Wanted to send the guy a message saying good luck. Calculated the roi and it was 800 days for used equipment!! LOL
P.s. I always do roi based on current conditions as both price and difficulty change over time. And in my opinion any roi over 12 months is ridiculously high. Especially for used equipment. Last summer we were calculating roi at no more than 6 months at lower crypto prices.