The late 126 cars were really the best. It seems that Mercedes always makes the best cars right when they change models. The 126s can be expensive to maintain if you don't watch who's doing the work, but the 140s are really! expensive and troublesome. Its hard to keep every little thing working at all times and those things like window regulators and AC evaporators and P/S leaks and door checks and radiators and control modules ect. ect. need immediate attention. That said if you are a big person the S-class cars are the only way to go. A 7 series BMW while also a great vehicle ( when right ) is even a bigger headache.
I'm sure if you take your time you can find a peach out there. I'd make sure to look at it on a lift though. Headgaskets and trans leaks are common and the T-chain can't be overlooked. Bad body repair also is easily seen from underneath. I'll bet you find a nice southern car for 8 to 10 K. Good luck and happy hunting!