I've yet to see a MSRP. Based on GT & Shelby pricing, I would guess $40-$45K?
I like the Boss over a Shelby. Something about high RPM small blocks that I find more intriguing than a forced induction engine. Guess that's because my 340 Challenger used to whoop up on all those BBC Chevelles.

Their claiming 7500 RPM RPM limit on this Boss and 440 HP. With CNC heads, larger cams and a better intake than a GT 5.0, I have to think the 440 HP number is conservative. The GT is rated at 412 HP and some reports are showing 390 HP range on the chassis dyno!