I sell replica coins on eBay as gap fillers, educational handling examples and living history tools. I make very sure that the description is very clear that the coin for sale is a replica. Some of the replicas being made in China are obvious modern replicas but others are extremely good and might fool even an expert who examined the pictures alone. I sometimes have to stamp the coin with a replica mark myself, especially some of the copper coins. eBay has tightened things up but it's still a long way from watertight. If you mention the word 'replica' in the title or description, you get a heads up asking to make sure the coin is in the Coins>Novelty section. Even then, it's up to the seller where it gets listed, there is a George III Northumberland shilling on eBay right now that is obviously from the same stock as those I sell for £4.50 per piece being offered as an original. Be vigilant....