I use the obvious thrift and second hand stores when I’m out and about. When I look online the best site I’ve found is HamiltonBooks.com. I’ve also been checking out gruv.com, which I found when I went looking to preorder Deathstalker. I’m curious if there are any good sites I’m missing out on. I’ve been getting into UHDs but some of the prices seem outrageous.
Locally we have Kijiji and Facebook marketplace. I was for sales on Gruv and eBay also.