24 hours and facepalm
 

Hello!
Brand new member here! Just picked up a 2005 E320 (non CDI). Found a gem in near mint condition with 90,000 miles (albeit once one key...)! Managed to pick it up for $3,700. Not a bad deal!
After roughly 24 hours, I managed to lock the key in the trunk. Took a locksmith about 20 min to pop a door open, granting me access to the cabin, which as we all know, the trunk release will not work. After another 20 minutes of grumbling, I stumbled upon this site which directed me to a little trick of removing and replacing one fuse, and viola! My ineptitude was saved. Thus, I am now a member here to glean all sorts of other tips, tricks and dive headfirst into the community of W211 ownership. Happy to be a part.

Welcome! One of the first things I did was get a second key from the dealer. It wasn't cheap but worth every penny.

x2 on second key.
I bought car with keyless go last fall with 1 key (talk to PO and the key with manuals were stolen at auction) and was shopping around for new key.
Las Vegas quotes were $580 +1xx for programming.
But since I still come to San Francisco area, where I used to live, I remember remote MB dealer who was always giving me good quotes and they sold me the key for $350.
Worth shopping around and consider buying they key on your vacations when necessary
Now for guys who have talents for locking the keys inside, I advise to hide the knob inside the car, while put the metal blade outside. You can use magnetic box, but I rather put the small blade inside a blinker, that can be easily removed with screwdriver, or just use duct tape to stick it in inner fender.
This way you have double security and still can get car moving when you lock, or loose the key. .

Here in NYC the key was $275 programmed from Helms Bros.