I had a locksmith make a key for my '87 300E years ago. Obviously it didn't have the IR system. However, as good as this locksmith was, it took him two tries to get it right. I just wanted a spare key, just in case I lost the only one I had.
I now need a IR key fob for my Cl600 and expect to spend over $200. My mechanic gets a 20% discount from the local dealer and will give me the discounted price. Something else I learned was that MB supplies their own batteries with their keys. They have higher voltage rating than the ones you buy at Walgreens or Radio Shack.
Anziani
'97 Cl600 51K