I HIGHLY recommend, if you're wanting a 2nd gen MINI, to go with a 2011-2013 as they have the N18 engine. The 2007-2010 come with the N14's that have very common issues with valve covers leaking, HPFP failure (warrantied by a dealer if you're within the mileage and year for replacement), timing chain "death rattle," massive carbon clean up issues that need to be cleaned every 50k miles and a few other quirks. The N18's got rid of a lot of these issues, although I have seen the HPFP issue with the N18's before. I have a thread on that here:
http://forums.pelicanparts.com/bmw-mini/936930-hpfp-warranty-replacement-n18.html. However, they will be much more reliable than the N14's. Now, if you're looking at the non-turbo issues, then that's a whole different story and you'd have less issues with both the N12 and N16 (2007-2013).
I'd highly recommend you find a low mileage N18 with all the service records. You'll want to make sure fluids (especially the cooling system) have been serviced like they should be. Change the oil every 5,000 miles and make sure you change filters as well. Let me know if you have any specific questions as I'd be more than happy to answer them. Hope this info helps.