Very hard to say exactly but as rough ballpark figures IMO this is roughly how the market sits:
1970 Challenger project car (with non-#'s engine) $2,000 - $6,000
1970 'Cuda Project car (with non-#'s engine) $5,000 - $12,000
1970 Challenger Driver condition (needs some good TLC) $12,000 - $18,000
1970 'Cuda Driver condition (needs some good TLC) $18 - $28,000
1970 Challenger in show condition (number 1-2 car) $40,000+
1970 Cuda in show condition (number 1-2 car) $55,000+
1971 Challenger in show condition with a 383 (number 1-2 car) $30,000+
1971 'Cuda with in show condition with a 383/440 (number 1-2 car) $75,000+
1972-74 Cudas and Challengers vary plenty but you can pick up many good bargains whether it be a rolling chassis or a fully restored 1974 Rallye packaged Challenger. So it's truly hard to gauge how the market is due to the fact these years haven't really found their true market value ranges yet. IMO in 5-10 years we'll see the later year cars settle down in a price bracket range, definitely higher than now.
4-Speeds usually fetch more than TorqueFlites unless they are on a low production car say for an example: 1-27 Automatics built etc.
Also, high optioned and rare option cars eg: Sunroof or rare color combo cars hit some high price ranges due to investers.
The HEMIs are well out of the range of your average Joe HEMI 'Cudas being the top of the dollar value.
0.02c
Cheers,
NZ440R/T