As several end-users have shown interest in the domain clearly it is worth more than $20-$30...
Do a bit of research about the end-users such as size of the companies, what kind of domains they already own and how important their web presence seems to be. Without knowing anything about the end-users IMHO an asking price in the $xxxx range could be a good start.
To back up your price you can compile a short list of similar sales.