Here's the current price list. I sourced my converter from Precision of New Hampton. It was around $1200, and bought the Reid Bell Housing from Jegs for $300 something. I did make my own cross-member, but US Cartool offers one now as well. It did require modifying the torsion bar cross member, but not the floor.
The stage 3 trans is said to handle over 1000hp. I'm only putting out 500'ish at the crank, so I went with the Stage 2.
Extreme Automatics