How do I know this? Because I’ve done it! In late 2013 I was still struggling to earn a respectable income online. I started up a keyword research service and marketed it to just this blog audience. It turned out to be quite popular. Basically – I would find niches using Long Tail Pro then create Keyword Research Packages. Each package contained usually several hundred keywords with KC scores calculated. I was selling these packages for anywhere between $97 to $147. I even sold one single package for $597! That one had very high search volumes and very low competition.
Because great content requires a deep understanding of the main idea (e.g., “ac repair houston”) and the supporting subtopics that require coverage (e.g., “central ac vs portable ac systems”) and the common issues that users seek answers for (e.g., “freon,” “refrigeration loops,” “coolant refills,” “troubleshooting”), the effectiveness of a keyword reporting tool is only as strong as the SEO pro using it.
They’ll show you information like how many external links the site has, the number of Facebook and Google+ shares, estimated visits per month, and its page authority. All of this is valuable intel that can give you insight into where your page could potentially rank against them, without needing to do more research with a separate tool or on another page.
The WordStream suite of Keyword Tools is an integrated and actionable set of keyword tools designed to help search marketers with keyword search, keyword suggestion, keyword grouping, PPC keyword research, keyword analysis, long-tail keyword research, and negative keyword discovery, going beyond the capabilities that a typical free keyword tool can offer.
Be sure to re-evaluate these keywords every few months -- once a quarter is a good benchmark, but some businesses like to do it even more often than that. As you gain even more authority in the SERPs, you'll find that you can add more and more keywords to your lists to tackle as you work on maintaining your current presence, and then growing in new areas on top of that.
The final sales price was based on a multiple of trailing 12 months net income (i.e. The average net income over the most recent 12 months).  I feel like I got a very good multiple.  I had talked to the brokers at FEinternational, Quiet Light Brokerage, and had viewed sale history of other similar companies, so I know the price I received was very competitive.