You’re going to have a hard time getting a direct answer on this one, but you can make a very good living at this. I make more as a webmaster than I do at my full time job, although I’m not willing to go into any more detail than that. It’s like anything else though–20% of the webmasters make 80% of the money in this business. No big deal; just work hard and make sure you’re in the 20%. (And actually, when it comes to affiliate marketing, the Pareto Principle’s numbers are a little different–probably more like 10% making 90%.)
Congrats on the initial success!