I have a site which i make 3 months ago and 4000 + users Registers and 150 +users Registers Per day and i make 300 t0 400 $ per month from this site... check out my 2nd signature and tell me what's my site worth, it's fully Custom designs and Licensed Vb...
Have you checked out one of the many site worth websites? They all will tell you something different, but it'll help you to get a general idea. I use dnscoop.com most of the time, but there are many others (just google it).
your site is worth as much as someone else is willing to pay for it. But if you are averaging 350USD a month you could sell it for 3500USD. If someone is interested though and if you've got lots of interested people, you could get a lot more for it greetz, jobic
A site is normally worth between 10 and 24 of its monthly revenue. dnscoop.com is not acurate, you wont get those prices.