I'd go with an LS. It has everything the GSR has except leather (which I consider a detriment as you tend to slide around in the seat more in the corners), and it runs the B18 A or B. The GSR was the B18-C VTEC engine which makes boost trickier. That and the LS is much less likely to have been beat on than the GSR since all the racer wannabes went with the GSR.
Superchargers can be anywhere from $500 to $2000 depending on where you buy them and whether you have them installed for you or not. Buildup is unnecessary unless you plan to run more than 9lbs of boost (the Jackson Racing supercharger, which is pretty much THE supercharger to get for Honda motors, does not run more than 9lbs with it's stock pulley, so you're pretty much ready to go with it). If you're running turbo, the most common way to do it is to raid the junkyard and pull one off of a mitsubishi, then run the plumbing yourself.
An intercooler is highly recommended, and don't do what one guy I know did and forget to put a blowoff valve on unless you want reduced performance, more likelihood of breaking (happened to him) and you want your car to sound like the Jetson's car every time you get off the gas (this part was really funny actually).
The only big caution is to make SURE your cooling system is up to the task. If your radiator has busted fins, replace it. It's having to cool an engine that generates more heat, while being blocked by both the air conditioner AND the turbo intercooler. Overheating is the most common problem in Hondas when the turbo is installed by someone who doesn't do the groundwork right.
It sounds like you don't have a lot of exp. with turbos, so if you go junkyard diving for one, be sure to take someone along who does have experience so they can examine the turbo with you and make sure it's OK - the junkyard will charge you the same whether the bearing is bad or not
If you want to run more than 9lbs of boost (you won't, at least, not at first - 9lbs on a lightweight Honda is a serious kick in the pants), you'll need to build up the internals to take it. Like I said though, that's gonna be a long way in the future for you - you'll be having too much fun with 9lbs to worry about messing with buildups.