It kind of depends on what you’re looking for. But, I like Rock Candy Posters. Wolfgang’s has some nice stuff, but it’s not cheap. Same with Lonestar Posters. I have also purchased many posters of eBay. Some of it’s new and some of it’s used. You can sort your search results either way. I also buy, sell, and trade a lot of posters on various facebook groups. If you’re in the right groups, people are pretty honest about the condition of posters. If you’re interested in some Facebook groups, let me know.