Pity the poor 'SLC. Twas the top o' the line at one time ya know. I've got a '76 w/ 130K and consider it to be one of the better car available for under 10K here in So. Cal. If you've got one to sell, there's not many buyers. If you're looking to buy one, you may be able to find a pampered pet that somebody will unload for under 10K.
I got mine for $5,600 and have had to replace the timing chain, rear-seal, drag-link and flex-disc. I'm good with wrenches so I've done quite a bit of work on it myself. The interior is in good shape as is the body and paint. So if you are mechanically inclined and have a good starting point, you may be quite pleased with what you get.
When you consider it, there are few cars you can get for under 10K that have a serious chance of appreciating. The SLC is kinda-like the Goldie-Locks of cars; not to big, not to small, not to fast, not to slow. It's also big-enough to make you feel nice and safe (relatively). Besides anybody (you can substitute a different word here) with a little money can go out and get an 'SL. That's a no-brainer. You'd have to know your cars to go out and get an 'SLC.
The biggest drawback about my '76 is the fact that the catalytic converters are located under the hood. The heat retained in the cats will cook components over time. 77's moved the cats downstream and solved the problem.
75's had early smog gear and electronic ignition, which caused problems. 76 and forward had mechanical CIS injection.
If I had to do it all over again, I'd get a 77-79 450. 77's and forward also had Automatic Climate Control, which can be problematic. Take your time, you'll probably find a car that some old-timer has kept up in perfect shape and now can't get rid of it.
Of course, I'm looking for a 450 SLC 5.0 or a 500 SLC. Very rare, big engined, lightened up SLC.
So to summ it up, I've got a relatively rare, good looking car, with available parts, that's totally paid for and in excellent mechanical shape. You don't need a special computer to diagnose the car and tell you what to replace - so if you're mechanically endowed, you have something to work on in your spare time. Also, if I get whacked in it I feel pretty safe (they don't call 'em Panzer Wagons for nothin') and know that I can go out and get another one without much fuss. You should go out and get one to.
P.S. Get original mag wheels, they make the car look much better than the plain old hub-caps.
P.P.S. Check out this site to see what a European felt was worthwhile to restore. http://cstraub.swissworld.com/mercedes_450SLC.htm