to my eye, the 05~09 was a sharper looking body...exterior looks aside, the pics ive seen of the '10 interior look GREAT. The shelby upgrades are pretty minor I think, likely 540 hp or 500 hp would break the tires loose before getting there any where legally...doubt you could floor it at under 60-70 without going up in smoke- not that it wouldnt be fun

I think with the heavy discounts on 08/09's still on the lots, you could probably get one way under msrp, but the '10 will likely be marked up for a while just because its 'new'.