Crazed, I am in the same boat you are. I am gonna be getting a 240 soon and I don't know which I want.
The way I see it is like this..SR20 Pros:Factory turbo motor, lighter, huge aftermarket, easy to make big numbers, may have a better head (not sure yet), probably lower miles, cool valve cover
Cons:Much smaller, has to be imported, if you break something you may be SOL, wiring, wiring, wiring, iffy valvetrain, might be harder for emissions (not a problem in my state, YMMV)
KA-T Pros:Iron block, big torque, stock parts are cheap as hell, already has a nice setup (oil squirters and whatnot), more streetable, no wiring or other BS to mess with, nice valvetrain
Cons:More than likely will have to do a rebuild due to mileage, requires a bit more attention to detail to make sure you dont break something, aftermarket is pretty limited, turbo kits are very expensive
As far as price goes, i think in the end they probably come out to be pretty close, although I mentioned turbo kit prices, you gotta consider a clip+shipping+all the misc stuff you'll need adds up.. so it evens out more or less.
Personally I've come to a bit of a stalemate. :P Anyone who has more to add or suggestions please chime in.