I put an NA 3800 series II in an 84 Fiero we use in Lemons racing. We picked the engine up from a pick-a-part on a half price sale. If you have time to do it yourself I tink thats the cheapest way to go. There are always a few supercharged engines out there. We took a battery and did a compression test and checked oil/bearings before we pulled out the engine.
For the swap, I would buy mounts from a reputable source. If you haven't already, the pennocks fiero forum for information. Our swap was pretty easy since we eliminated a lot. The wiring is by far the most involved process.