User blog:Monster Blood Drive/Where to Shop for Old Goosebumps Books

I've been wanting to buy some of the out of print Series 2000 and Give Yourself Goosebumps books but I also want to be sure I can find and get them at legitimate quality from trustworthy vendors. So to everyone whose collections include the likes of GYG, Series 2000, Tales to Give You..., and etc, where do you buy those books and are there any reccomended shops? I apprecite any feedback!