All depends on what engine you choose (obviously B18c5's and the like are gonna be more than a B18b, supply and demand), if your going to install it, if not where your getting it installed at, how many miles the engine has on it, is it JDM or USDM, are you rebuilding it while it's out of the car, etc. But since you mentioned GSR (B18c) we'll use that. Figure around 3K for the engine (complete changeover, tranny, ecu, etc) You find one cheaper, or you may find one for even more. Figure around 500-1000 for labor, again depending on who does it. There are outstanding deals out there, you just have to look. I've seen B18c5's going for 2K, and B16's going for 4K, you just have to look around and get a good deal. So that's around 3500 (give or take a few hundred) And then it adds from there, if you build the engine, add bolt-ons, have them change all the belts, etc.