I was just at the restoration shop I use in NC, and he has a customer who owns a '70 Challenger 440-6. This guy just found a '70 'Cuda 383 4-speed convertible in an upstate SC paper for $5000. Talk about being at the right place at the right time. I saw the car last weekend while visiting my car, and it was extremely nice. Dark green w/ front rubber bumper, light package, rally dash, solid floors and trunk...just needs panel replacement, fuel tank, stuff like that. These kinds of deals are VERY few and far between, but it did let me know that they're still out there. I'm encouraged! Good luck with your quest.
Winston