It is difficult to value a flash game. Games are worth different amounts to different buyers... and most buyers will try to pay as little as possible so if you don't haggle or get lots of offers the money you get can can be low.
I've literally seen a game get sold for $X dollars... where I know another portal (I've asked them for confirmation) would have paid 10X (10 times as much money) for the exact same thing.
Having said that... I'm still very new in this scene. I would love it if anyone would send me a PM (or email) sharing the details of their transactions. I'd be willing to share further details on AR3 as long as you agree to not post them publicly.
If I get enough information hopefully I can write up some general 'pricing guidelines' to help people decide what their creations are worth.
