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Buying from the apple store has one year warranty, which is nice...
 
Personally I'd avoid Ebay. Apple has an excellent return policy (whereas your ebay store want 15%).

You should also consider buying from the Apple Refurbished Store (though stock does sell out fast).
 
Apple doesn't have any refurbished Retina's. I'm thinking about getting an older computer now and wait till revision 2 comes out or something, to fix the Image Retention. Just not sure when that'll be coming out.
 
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