Actually, Bud, the R/T with the 5.7L HEMI and (currently) MDS doesn't get hit with the gas guzzler tax. I believe EPA estimates for that motor (with the 5-speed autostick) are 18 mpg combined. Ours averages 25+ mpg on the highway, and 16 mpg around town. No GG tax on that.
Since the MSRP on the 2008 Challenger SRT8 is $37,995 ($40,095 with the tax imposed and destination charges added in), and the 2008 Charger SRT8 base price is $37,030 (add the GG tax and destination charges and you're at $39,805) the difference of $290.00 is what I'll base my guesses on.

My Prognostications on Base Prices (including destination charges);
2009 Challenger SXT with 250HP V6 / 4 speed automatic transmission - $26,795.00
2009 Challenger R/T with 5.7L HEMI with MDS/VCT / 5 speed autostick - $31,695.00
2009 Challenger R/T with 5.7L HEMI with VCT / 6 speed TREMEC - $31,545.00
2009 Challenger SRT8 with 6.1L HEMI / 5 speed autostick - $38,145.00 (plus $2,100.00 GG tax)
2009 Challenger SRT8 with 6.1L HEMI / 6 speed TREMEC - $37,995.00 (plus $2,100.00 GG tax)

Those are my guesses. Anyone else care to take a stab at it?
[:-]