2002 CLK 320 or 430: Cabrio Purchase Tips?

[Benz Mondi]

Our first choice is to replace my '91 SL with a 1st Gen (separate front headlights) CLK 320 Cabrio because it's a 2+2 seater. I used to have a 2+2 with my Ferrari and we really enjoyed being able to tote 2 more people for an open air drive to the country side at much less than freeway speeds so that the back-seaters didn't get beat up by the wind. The back seats on both the Ferrari and the CLK's are about the same so no issues with the "shoe-horned" experience.

I seem to have trouble finding enough 320 Cabrio's to consider. Almost all that I see for sale are the 8 cylinder, 430's.

Cabrio only Questions:

1. Any purchase tips?
2. Why so many 430's for sale and so few 320's?
3. Any unpleasant ownership experiences I need to be aware of?
4. Is the cost of ownership of the 6 cyl 320 less expensive than the 8 cyl 430?

Thanks.