Valuation is subjective. Usually buyers will value on a basis of prospective earnings at some multiple. This is then checked against comparable acquisition multiples and discounted cash flow analysis to triangulate a value. Where you use debt as part of the valuation methodology you can also use a leveraged valuation basis to compute value.
In your case since you are removing the affiliate accounts with a track record (which a buyer could evaluate the average worth of a player and work out what the residual player worth is prospectively) the only valuation basis that makes sense is a multiple per user on the sites. The next debate you will have then is how you define user and whether it is an active or an inactive user.
There are plenty of sites who would, if the site were dressed up for sale, consider buying the traffic but the best bet would be to get someone who knows a bit about valuation and presentation to do a teaser and then work on your behalf to pitch to the bus development directors of some of the more acquisitive listed groups that could monetize the community effectively. This would be a smart way of going about it! Don’t open your kimono publicly whatever you do!!!
I have a bunch of experience here so pm me if you have questions.
cheers
Devendra