I find Justin Tadlocks forum the best $25 bucks I have EVER spent. I know Jeff knows how it works, but for anyone who hasn't been, it's $25 a year to join. Now anyone can go, but you have to be a member to see Justin's answers/posts. He only answers questions about his work, but it's great. I consider it invaluable as a user of hybrid themes. I'm sure it requires a fair amount of effort on his part to answer the forums, but I can't imagine a better model.

Maybe you could hire some folks to answer support questions? Split the profits with them? I'd pay $25 a year for that, but I'd have expectations. $90 a year though...