Is the website currently making any net profit? This would be the easiest way to provide an estimate of how much the website is worth. You have a really nice website and the concept is fascinating! Your traffic isn't that good and your alexa/link pop leaves a little to be desired.

Based on what I currently know. A nice functional and attractive site, reasonable traffic, I would probably say about $500. If it's making $500/month then obviously it's a whole new ball game....probably into the $x,xxx.