eBay has become a haven for scammers, and thieves, to sell their stolen merchandise, and rip people off.
There are a few things you can do and watch for to protect yourself from buying these kind of products.

-If it doesn't have the power cord, and AC adapter, it's probably stolen.
-If it doesn't come with the backup and operating system discs, it may be stolen.
-*Make sure for this one* Make sure it has the main password, the admin. password(and preferably the user name as well). Without this password, you cannot update the computer, and may not even be able to access the operating system. If the seller cannot provide this with the computer when it's sold, it's probably stolen.

If you find a apple computer you like, here are a couple other things to ask the seller about.

-Are there any dead pixels, scratches, or damage to the screen?
-Are the power cords frayed or faulty?
-Are the hinges damaged or loose?
-Does the DVD or disc drive work perfectly?

There you have it. A few tips to help make a hard decision. Happy bidding :)

*If you have anything you would like me to add, please feel free to message me.*