I'm glad you found us here as well. The poster thang is an addiction (for some anyway...like me) and/or a wonderful hobby.
The eBay seller... Let me guess. TLOCE? If it is him, while he does sell some legit stuff, steer clear. He is known for FAKES!
The auction houses can be pricey, too. EMovie is your best bet--no hidden fees for buyers (just added shipping costs) and great at having accurate descriptions. Most of my shopping is from eMovie.
Anyway, welcome. Happy poster shopping. Feel free to share your collection when you can. We'd love to see it.
CHEERS!