Hi there

I have a 98 SLK 200 (not a kompressor) which has not an A/C installed.
I'm thinking of installing an A/C and I wonder
a) whether is it worth doing it or not and
b) whether to install a genuine MB A/C or an aftermarket one.

Has anybody done something similar or heard or read something?
Are there any manufacturers (if its not a genuine one) that you can suggest?
Am I going to have problems after installing it?
What would be a fair price for a genuine and after market A/C?

Thank you in advance