New Smart Key? Buy 1 off Ebay?Good or Bad?

Ok i gotta question? i just got my car at the end of June and when i got it, it only had ONE smart key. I've loooked on Ebay and found keys and saw them for sale..but never knew if it'd be safe to buy one and see if the M.Benz dealership could or WOULD program it for me. i 've called them before and this guy on the phone said that you shouldnt buy them off ebay cuz it was for a different car other than yours. Said that you should buy them from the dealer so it'll be right for your car...what sucks though..is that the new keys are like almost $200. Anyone have any info on this key problem... i just want to know if anyone has ever bought a different key or one on ebay and had it programmed? the guy said it wasnt possible, but why would people sell them on ebay and have good feedback from before?
thanks,stephanee

STAY A WAY FROM THAT, If you read even the fine print on that e-bay post it never says anyhing about the key working your car. The only place you can get a key for your car is the Dealer, Because thats the way the manufacturer wants it. Buy it any where else and the only thing you just got is a Christmas tree orniment.

its better if you buy it from the dealer itself, it though little costly, but at least it will save you the time getting it reprogrammed again. i own a little older C class, once i lost its original key, i got umpteen no. of responses from other ebay like portals, i bought one and dealers couldnt reprogram it. ultimatley i had to buy it from the dealer only (and he took 3 weeks to deliver)

vikram
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don't trust it. just go to a mercedes dealer and get one off of them. At least that way, you know your money isn't wasted on a useless key.