Things to watch out for...
 

I am currently looking to buy a 2nd Gen RX-7.... probably a N/A with a 5speed. Most likely itll have around 100k miles on it.

so i was woundering what are some general things to look out for when buying one of these cars used, also what should i have it checked for?

dont buy one with blown apex seals. rotary engines can still run if they are blown. get it compression tested. look for even compression on both rotors.

Check the coolant (preferably maintenance records) -- it shouldn't look too grungy. The coolant seals on these cars can go bad if the coolant isn't changed every year or so, and that means an engine teardown / rebuild <~ 2500 bucks!)

http://www.aaroncake.net/RX-7/

http://www.kbb.com/

Evil tips:
1) Do not get one with an automatic transmission.
2) Decide whether to get a TII or NA before your purchase. Note that the insurance and gas mileage are about the same, but the TII will cost more to purchase initially and to maintain.
3) If you live somewhere with emissions standards, make sure that the car will pass before you consider it.
4) Make your $ offer according to what the car (condition, mods, color, etc.) is worth to you, not what it is worth to the owner.
5) Don't worry about getting a certain year or model, just look around until you find one that you like.