We've tried hatching from EBAY eggs, with not much success, probably less than 10% & not always what was expected either
I agree that there are some unscrupulous folk out there & as Kaz says - look for the feedback before you buy. You may find it better to go through breed clubs if you are looking for something specific - they may find you a local supplier, if not be able to put you intouch with a reputable breeder who is willing to put some hatching eggs in the post for you.
Alternatively, you could put a post on here
Another tip, if you do get hatching eggs through the post or have travelled far with them etc. let them settle for 24 hours before you set them.