I read a thread a while back where the discussion was about buying SSD's on the open market for 2013 and later Mac's but I can't find it now. I just wanted to share that I purchased a 1TB drive on eBay. Bought it from Korea the home of Samsung. 5 minutes to swap out the old for new in my late 2013 rMPB and it booted fine directly into the setup screen to set language. No issues at all after a month of use. The 512GB out of the rMBP made it's way into my wife's mid 2013 11 inch Mac Air as she was struggling for space for photographs and video. The 256GB out of her machine will go into an OWC USB3 case to use for storage / backup.