Terrific sounding domain, but not as popular as it sounds...almost too broad for the specific use of a single real estate office...unless it's a franchise or something (156k on google).
Even so, this is a tough one to appraise. Depending on how bad a broker wants it (and I'd think someone would, even as a .net), I'd guess most offers to be in the range to be mid $xxx to high $xxx range. However, I'd also guess negotiationg would get you a bit more. I wouldn't sell for under $1000.