Nice cars on that Frank Collection site, but man they are a huge violator of labeling everything with big wheels and a stroker big block "pro touring"
You will definitely find the best price and value on the private market -- not from a broker/collector/dealer like that. Most of those cars are very overpriced.
Use all the classified sites you can find, and a national craigslist search site.
Good luck. You can pick up a very nice car in this market for $50k.