Value questions are usually nearly impossible to answer because it's such a subjective thing. Prior to this car becoming available, was a '72-'74 'Cuda the car that haunted your dreams? Does this one have every option you want, or close to it? Are whatever options that are missing livable to you?
I'd have paid three times more for my Challenger if it were a double-black '73 340/4-speed non-console non-Rallye like my first one was. The car I bought was a '74 318/auto non-Rallye, but I'm OK with that because numbers aren't really that important to me. The price was extremely right, too... but if it had been a 'Cuda, I'd likely have passed entirely because that wasn't what I wanted. It had to be a Challenger, period. I can build what I want and since I don't plan to sell it I can get a little crazy with the spending now and then.
If you like it enough and can get it for a price with which you're comfortable in terms of resale, then go for it. On the other hand, if you'd really rather have something else (a different year, a Challenger, whatever) then keep that money in the bank and find the one that really spins your beanie. Don't pay market value for something you don't absolutely love... if you have to sell it, market value may be down or simply hard to get.