Find out who it is that is interested.

Depending on who it is, you could also flip the question and ask what they're willing to pay. They're going to hit you with their low number and perhaps even try to justify the cost. However, there were a couple times when I did this with a high value domain and the potential buyer offered something in the low 4 digits on a domain worth high 5 to low 6 digits -- the buyer knew it -- but the buyer was testing the waters to see if I knew the true value as someone not knowing much about the value may let it go thinking they're getting a quick couple thousand, but it in some cases it can't hurt.

I've bought and sold domains myself anywhere from $100 to $250,000. Your one word domains with a meaning will typically have a good value. Even a domain with one or two letters of significance and an important word (where the two combined have a meaning - easy to remember) can fetch a pretty penny. For example, ireport.com went for $1 million USD.

You can always get an appraisal from someone like afternic, but there are things appraisal's don't consider such as who the potential buyer is or if there is a specific demand for the name.

I'd ask yourself, is it worth anything to you at the moment? Any plans on using it again or any potential value on your side? If you have no plans, I'd then ask myself what would I be happy with? ...but do find out who the buyer is and establish a benchmark for what it's likely worth.

Good luck!