How to Prevent Buying a Fake Collectible
Be wary when the seller requests privacy. While this would be acceptable during some higher-end sales, those who sell counterfeit merchandise request anonymity because they don't want to be called out by experts and have their reputation tarnished.
Always ask for authenticity documentation that you can have verified by a third party.
Buy from reputable sellers. Collectors take pride in their knowledge and have no problem in educating others on what to look for in buying memorabilia. Check ratings and reviews of seller online.
If it's too good to be true, it probably is. Be wary of items that should be priced much higher if they are indeed authentic.
Check to see if the dealer has a large amount of inventory of the same signed product.
Avoid private bidding. Why would a dealer not want to advertise high bids for an authentic product?