they are not going to pay you a million dollars for the domain, and they could go to the international domain name resolution board for grabbing them, as Entercom did with the person who grabbed HowieCarr.com.
One of the BCN DJ's had their name squatted and thy also took legal action IIRC
Most savy companies register all good domain names early on in the process of flipping. That's one of the ways we can figure out a flip before it happens.. we go to Whois and see what has been registered and to what company.
There are enough ways to format a domain so a station can always find something they can image with without being extorted.
Neither of the stations I work for have their calls as a domain, and even when we could have had them for nothing we didn't take them.