More seriously, you can get them on ebay, but I imagine they would then have to be programmed by either a dealer or one of those backstreet places. It's not going to be cheap.
casey
i asked this question 6 months ago,all i got was sarcasm on here, forget e bay as mercedes will not repeat not reprogramme used keys,and i have yet to find somebody with the knowhow to do it on the quiet.
good luck taff.