I, too, would build/buy (buying would be cheaper in the long run) a car that can fit both NHRA and IHRA both, for all the reasons stated above. You have more options. Racers that live out west, for example they are, for the most part, are stuck as NHRA only, as there are not many IHRA events out there as NHRA. Also, Bowling Green/Ohio Valley do not allow IHRA cars at their monthly combo's (which is dumb, but whatever).
There are quite a few cars on here for sale, some as low as $5,000 (mine is one of them). Check them out, and don't be afraid to go to a race or two and ask questions of fellow S/SS racers. Also it will depend on how quick you want to go. Some people have the mentality of "if it runs slower than 12.00, it ain't a racecar to me". Others have made a living in slow cars (again, me being one of them). To each their own. One of the wonderful things about Stock--you can run an 8 second new factory car, or a 16 second FWD car, or anything in between, and have fun doing it.
