Well, more importantly was this domain name ever a developed site? Or, is it just a strong keyword or combo of keywords. If the ladder, how much revenue is the domain name generating - This is most likely where your price should come into play.
Monetize my friend!
Get a good site made for it with actual content about the topic, take some of the profit your making with it and have someone "good" on one of the freelance sites make you a good minisite with original content on your type in topic, then insert your ad campaigns and watch your profits triple-quadruple over what you were getting from sedo.