Like this previous posters have said....lots of variables. Is it matching numbers? How much rust? Running? How complete is it? (Like do you have the expensive parts like the grill, hood, dash, etc?) A 73 'parts car' - lots of rust, not running, etc is worth $2-4k. A running, mostly complete project car is going from $4-10k, depending on condition. Daily drivers are going for $9-16k and perfect, show cars are going for $20-30k. This is what I've seen actually sell on ebay the last few months, not what people are asking which is a lot of times a lot more. Condition is everything, which is why we'd need pictures and lots more info.
I've been shopping for a 73-74 Cuda project car for a good 6 mo. now, so I might be interested in buying, with more info.