Welcome to the forum! The CF4 is a stout speaker that makes tons of bass. The largest speaker in that line, actually. Pics would help more accurately put a value on them. They have an issue with the cabinets coming apart over time. Have you noticed that anywhere? Especially the back. In absolute mint condition, clean grills, good corners, no cabinet issues, all 4 drivers functioning, etc.....you may see $800-$900. That would be top dollar I would say. $500-$700 would be what you could expect. That's my opinion though, someone else may have a different opinion. If you can, get some pics up, I'd like to see them!
Thanks so much for your response; very helpful information.