Here' s my experience with my 95 GSX.
I bought it with 29K on it. Bone stock. I have done all the free mods and switched over to a 1 G BOV with all hard pipes. Nothing done to the engine except for little stuff like plugs, wires, MBC just basics.
Replaced the timing belt and O2 pump at 80k. Didn't know anything about the required 60k replacement inteval.
Replaced struts, brakepads and turned the rotors @48K
New Clutch @ 87K

Problems I have had are:
Crappy Door Handles
Idle Control Sensor
Rear wheel bearings
Misc interior probs
Tranny ginds in 2nd once in awhile

The car now has 120K on it and runs fine. I don't race at all. Been on the 8th mile strip once and that was all I needed.
The biggest thing to consider when looking at a used vehicle is how it has been maintained and driven by the prvious owner(s). I have heard all the horror stories as well but it always seems to be a car that had been rodded to crap that causes the problem.

These are high maintenance vehicles. Everything seems to cost more and needs to be replaced more frequently. So you are gonna be dumping some money into it. The more you mod and tune the more money it's gonna be sucking from you.

Hope that helps