I've bought a fair bit of paper off Ebay. All came from supposedly pro labs. All was supposedly well stored. The Kodak paper has been fine. The Fuji had problems. The worst part is the Kodak paper was much older then the Fuji.
I don't think buying potentially bad paper off Ebay makes sense when you're just starting out. Buy a box of fresh paper from your local dealer. This way when you have problems the paper won't have to be ruled out. Later when you know bad from good then you can gamble on Ebay paper.