Just for the heck of it I Googled 'Domain Name Broker' and didn't like what I saw. If you think the domain really has value maybe you ought to get some kind of professional involved, like a lawyer or the equivalent of Ari Gold on Entourage. They'd probably want to take a percentage, which is ultimately in your best interest IMO.

Several years ago a former client bought the domain Florist.com for a million dollars. Not much later, he sold it to the current owners for a very hefty profit. To you the domain might not seem too special. Be sure to get what it's worth.