There are significant risks to eBay. Macs and Mac notebooks are scam magnets because they are so desirable. 100% feedback is no assurance that the account is not hijacked, or hasn't been built up to 100% with shills.
Any significant discounts on new or near new Macs are almost always scams.
If you have to ask here, then you are probably not ready.
I would advise a new purchaser to look at the Apple refurb store first.