I agree with Simmo. You are selling a business, so you must look at it from that viewpoint. People selling businesses aggregate their income from the past X amount of months, usually 12 and then forecast their future income going forward. 3 years is a general rule of thumb from what I understand. With that data, you can see how much your site..
1. Has been worth
2. Will be worth going forward
I really have no idea how much your site is worth, and I am not sure there is a general rule of thumb for how much your site is worth. I guess some one else can make a stab at what it is worth…
Best,