Richard1,
Couple of comments. First definitely have the car checked over by a good mechanic to insure no mechanical problems exist. Also have the frame checked, you don't want a car with major frame problems.
Regarding the A/C performance I discovered something recently that made a huge difference on my car. My radiator recently cracked at the flange and I had to replace it. When I removed the old radiator I found leaves, pine needles bugs and dirt had accumulated between the radiator and the A/C radiator. This stopped airflow in the lower regions of both components causing mediocre A/C. I cleaned the area thouroughly and have noted cooler engine operating temperatures and ice cold A/C which I need to turn down in 105F temps. I'd imagine many 500's suffer the same condition and a little cleaning can make a big difference.
If your not certain which way to go regarding a C43 and a 500E I would test drive both and look closely at features/benefits to determine which meets your expectations better.
Good luck, it's always exciting choosing a new car.
