Probably "fake" is not always the right word. Many items I saw on Ebay are not really fakes. It is more question of age and quality.
It is no problem to take a "new" statue, digg them in the sand for a week, pour some water on it, let the sun heat the sand - and after quite short time it will look old.
But most vendors on Ebay donīt say its old, itīs just what you believe seeing it. Thats one trick, make them look older.
The other trick is to take worst mass production and make a nice pic. You donīt say its old

, you just add a sentence saying your grandfather brought it with him from Africa (whenever this happened ...).