Date registered: Oct 2009
Vehicle: 2003 Lincoln LS V8
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
A couple of these cars are in different categories. I'd recommend determining what kind of car you want, besides a convertible, before making your decision.
The 350Z is a two-seat sports car. Given the other options you listed, I'd guess that's not what you're looking for. If it is, I'd cross-shop cars like the SLK, Z4, Boxster, S2000, and MX5.
If you don't need a lot of power or prestige, I'd go with the Solara. It'll be the cheapest to own and maintain, but it won't have the luxury of the 3-Series or CLK.
If you do choose the CLK, and you can find a 500 in your price range, I'd say go for it. Very few people ever wish they'd bought a less powerful car (except when they're filling it up).
Miles: I'd say look for a good CPO model, preferable with an extended warranty if you're worried about maintenance costs. If not, have a dealership (not the same one that's selling the car) do a pre-purchase inspection to identify any potential problems.
Whatever you decide, good luck!