Why don't you try BizEquity.com, perhaps this can help. BizEquity.com is a 7 step cloud based process online valuation tool that specialises in valuating small businesses, not unlike online. The small businesses algorithms they use have been devised by renowned small business valuation expert Scott Gabehart, who has had the experience of dealing with all kinds of businesses including online ones. I would say it's been highly accurate no matter what kind of business i try to evaluate. (Yeap, I've been playing around with it)
You can generate an estimate of your online businesses for free with no subscription required and get their full report which features 4 different business valuations and an in-depth analysis of the business's performance relative to that of the industry if you like the trial service.
Shall leave it up to you to check it out.. www.BizEquity.com