The 3 cars on your initial list that stand out to me, are; The BMW 330CI, the Ford Focus ST and the Nissan 350Z. Having said that, they are all very different. I suspect the BMW and Nissan have fairly close running costs, but both will cost more than the Focus to run, especially when bits start to wear out. You could also get a nice Honda S2000 for £10k, but, if you are having problems with insurance costs you may aswell forget that entirely for the time being, they cost Porsche Boxster money to insure, actually about £50 more for me, and I get far lower quotes than you.
I'd drive at least those 3 if you like them, and see what is what.