I almost bought a new RX-8 before I went for my MS6. I looked at the R3 but decided on the GT. The non-R3 suspension still handles great and the seats in the R3 are too confining. The GT has more reasonable seats, a sunroof, and a few other luxury gizmos that seem worth it (heated side view mirrors would be great here in WI!).
I was able to get dealers about $1000 below invoice by searching the inventory on Mazda's site, requesting quotes on specific cars that had the options I wanted, then seeing if dealers who quoted higher would beat the lower quotes, until nobody would go any lower.
Didn't matter though. I gave up on an RX-8 because despite the handling the engine was kinda gutless and the overall level of practicality wasn't all that great. I gave up on the MS3 because I really liked the motor but couldn't bring myself to go back to fwd. So I went MS6 because it had that nice motor but sends at least some power to the rears.
I didn't really look at the STi or Evo. I wanted more refinement. All the performance Mazdas have that, if not at German levels at least nicer than the rally-style cars.
S2000 as I recall has even less room inside than my Miata did. Handles great and has better oomph than the RX-8 but uh, do you use your car for practical shit? Driving a roadster as your only vehicle is a bit of a lifestyle change. I'm still kind of shocked when I give more than one person a ride at the same time. So if you're looking for something more raw then the STi or S2000 may be your cup o' tea but uh......have you driven these cars? Any opinion of your own?