I have two copies one played and in pretty poor condition, and One with the reels unused with the tabs still on them and stored perfectly for almost thirty years.
The guy Originally wanted 500.00 dollars for it, but He brought the price down to 250.00 so I bought it. I think the guy calls himself tahoe toys, being a toy seller of star wars figs, and transformers etc.
The pretty heavily used one was 65.00 bucks from Cloudcity.com so I guess you get what you pay for.
I've seen other one's still in their original mailing box go for a lot of money, still none of them have appeared on the market as unopened.
There are some rare radio ad reels for star wars, and the empire strikes back interview reels or lp are out there if that is what you mean by radio stations.