This business isn't the kind of company a VC would invest in, which means it's also not the kind of company that somebody would see and think, "We could blow this thing sky high!" (unless $8-10k/mo is sky high). It does have great potential, but there is no chance of it growing exponentially (like a social network or other highly successful SaaS). Because of this, I couldn't imagine getting more than 3 years revenue for it, and it's such a consistent income earner that it's not something I would want to sell for less than (perhaps) 8 years revenue.