Today I had a look on ebay and oh, god! So many cheap used GPUs! Used RX 580 and GTX 1060 at under $100?! Seriously? Looks like miners are selling used GPU as fast as they can!
Where are you finding GPUs at under $100? Used ones are still selling for $200+ on Ebay. At least the ones with auctions close to ending or with "Buy It Now".