R&D costs are sunk at this point; Subaru will price the STi at whatever the market will bear. Researching the 2.5L turbo engine might or might not have been a great idea when the decision was made to do so, but now that it exists it would be foolish to price the STi out of reach in an attempt to recoup the R&D costs.
I agree with the guesstimates of $29,995 and/or $31,995 (plus a few hundred, of course, for things like the stereo & floormats). $30K even is cheap enough to compete directly with the EVO, slightly higher price for slightly higher power, $32K and up and you'll start competing with IS300, G35 coupe, A4, 330xi, etc. That's just a gut feeling, but that's the decision I'll be making as a twentysomething with around $30K to spend on a performance sedan. At $30-$32 I'll buy an STi, save money, enjoy the power, and deal with the rather ricey wing. Price the STi any higher, and I'll go with less performance and more luxury.