I used Mckinney mounts on my motor and for 90 bucks, I had the drive shaft shortened by a guy that rebuilds driveshafts. There should be someone in your area that can do that. Save $300. Most swaps come with the injector harnace and the wires for all the sensors. It should also have the alternator and starter harness. If not, that is easy to adapt. Once you rewire a harnass, you will find that it isn't that hard and you can learn a lot in the process. Look at the number of wires Chris Rummel used to get his car running. Not many . Make sure you consider lead times for any item that you have custom made. That makes a big difference.
Just like others have found, nothing drops into an S30 other than the original engine. There are always modifications needed (like motor mounts and a tran mount). I do like the McKinney mounts. They are heavy duty and the bushings are far better than the rubber bushings that came with the RB. They look good to.
Some of the guys on this site found local shops to weld them a set and that should cut the cost in half if you don't care what they look like.
If you or a friend can make you own then they won't cost much at all.
Just my 2 cents.