Depends on many factors. Doing the work yourself or a shop. New, used, or short block. Swapping tranny. Etc. See MonkeyWrenchRacing to get an idea of parts costs. In some cases, it's cheaper to just find a used GT-S.
For just the engine swap, you're looking at a minimum of about $1000-$1200. That is if you get just used parts and do the work yourself.
There is more to the engine swap than just the engine. Exhaust, both intake and exhaust manifolds, throttle cable, ECU are just some of the things needing changing to make it work.