This isn't directly what you're looking for but it might be able to help. I've been looking in detail at Roush's (primarily stage 2-3) for a few weeks.
A stage 3, almost fully loaded, MSRP's for right around $52k with all their transportation and stuff added in. The dealer cost is roughly $45,200. You can get them in the high $47's if the dealership will deal, and lower 46's if you find a really great deal.
You can also get a stage 2 down to (the lowest price I heard) 37,803 with all the seats, stripes, gauges, louvers, pretty much everything added (
http://www.roushperf.com/mustang_st2.shtml for pricing). Stage 1's are about 2,000 less, so you should be able to get one with everything for 35,800. Those accessories add up to about $4900, so you should be able to get a stage 1 with no optional accessories for just barely under 31k.
The dealers really vary. I just moved between states. The state I originally came from had a few dealers, and none would deal much at all on Roush's. The state I'm in now has a few dealers, and two will deal and two slap big markups on them and refuse to deal. It really varies based on the dealership.