Should not be a problem for any Mercedes-Benz dealer. Just bring in your proof of ownership that should have your vin number and it takes about a week to get brand new factory keys master & valet. all for under $20.00 and a cup of coffee.
I just did this for my wife's 1992 300-E . Call Caliber motors in Anaheim Hills CA and ask for Al in wholesale parts they have the best prices. You can fax the information to them.

Happy motoring
Bob Geco
1992 300-E Sportline
Zymol waxes , Redline oil
cheveron Gasoline
pampered with loving care