15k to spend?
I would buy an earlier Integra Type-R. That would keep me satisfied until the end of time...
Well, at least until the Civic Type-R is released to the USDM
*cough* never *cough*
If you were to leave the Honda camp... M3's are excellent cars, perhaps a DSM, WRX's can be found for about 15k as well.
I would rather spend more initialy on a car that is great performer straight from the factory, can always upgrade later once you learn the limits of your car as well as your own limits when driving that car.