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It was $150 on eBay for my Macbook back in 2008. Now it is $200.

Apple changed their AppleCare policy some months ago. Nowadays Apple seems to ask for proof of purchase when activating the code and they don't accept eBay receipts. This killed those more or less suspicious eBay sellers who sold AppleCare for 1/4 of its value and then only emailed you the code.
 
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