If Apple did not ask for proof of purchase / sale receipt during your repair within AppleCare warranty period, you are pretty save. However, if they did, I am 100% sure they won't accept Ebay or other unauthorized apple reseller's sale receipt. They can be very strict if they want to. Just my opinion after some phonecall to AppleCare.
I bought an AppleCare off Ebay from the UK for my 11" MBA 2011, BNIB and authenticated by Apple within a week. Savings of more than SGD$100.
I believe it boils down to doing adequate research before purchasing online, avoiding sellers with shady records. Also pays to be able to differentiate between a good deal and a deal too good to be true.![]()
