Why is it so hard to find the 65-70 mustangs and 66-76 camaro?

ive been looking for a mustang fastback, 66 to 69 camaro or a camaro like bumble bees before he turns in to the new camaro which is a 76 model but it it is close to 70-75 , but i cant find any on craigslist or new papers or auto-trader. i would even take one that needs work. i Live in NC. do you know where i can find one of these cars. id prefer a fastback or bumble bee camaro. i would even take a kit car