Wordtracker is another service that requires an annual subscription to utilize all of its features. Their database is made up of 330 million search terms, collected from the major metacrawlers, Dogpile and Metacrawler, and is updated weekly. The search data they show is a record of the number of times the exact keyword or phrase has been searched in the United States over the last 365 days. As in the case of Keyword Discovery, this difference in default keyword matching type causes Wordtracker to display search volumes significantly lower than what Google’s tools show.

This might be the easiest way to make Long Tail Pro pay for itself. I’m pretty sure that the affiliate program is open to anybody (even if you don’t currently own the product). Simply get signed up and then promote it any way you see fit (within the Terms of Service, of course). If you couldn’t tell, I’ve been doing this for quite awhile via this blog and I’ve earned a healthy sum of money over the years as a result.
Can't go wrong with the Google Keyword tool, SEMRush and Google Trends. The Keyword tool for volume estimates, SEMRush to see what keywords competitors are ranking for/targeting, and Google Trends to make sure the traffic is actually coming from countries I'm trying to target. Gives a relatively accurate picture of when to expect traffic spikes and seasonality insight.
To be able to rank in the search engines is an art that must be understood and finding the right Keyword tool that fits into your comfort zone is a must. What I mean by ‘comfort zone’ is having a keyword tool that doesn’t confuse you before you begin even searching. Some go into far too much detail than is necessary. All you need really are good long tail ‘common sense’ keywords that other marketers may have missed.
Once I have a list of phrases, rankings, and volumes from these tools, I'll look to internal tools (maybe Excel, Access, or another database) to organize, classify, and forecast opportunity. This is where I'll estimate a competitor's traffic based on volume & position CTR, set goals for a target position, and estimate traffic based off that position's CTR and keyword volume.
"I rarely get excited about SEO and SEM tools...But, when it comes to keyword research it is virtually impossible to produce a quality worksheet without software. When I have to perform the same task for my customers, the process is even more daunting and time consuming...there is now a better way to manage huge keyword lists and this tool is called WordStream."
To get started with the Free Keyword Tool, just enter a keyword or search term into the relevant field. If you want to conduct competitive intelligence research into your competitors' keyword data, you can also enter the URL of a specific webpage to view keyword data for that page. You can also enter your industry and country to see even more accurate results; it's not unusual for the cost-per-click and other metrics to differ widely from one country to another, even for advertisers bidding on the same keywords in the same industry. 
"Our whole team has a copy of Keyword Researcher, we use it for everyone of our client's keyword research for the 'Long Tail' and we use it every day to come up with blog post ideas and ideas for guest posting. We couldn't live without this tool. I have used every paid keyword research tool under the sun, and this by far is my favorite tool for mining the Long Tail."
Customize the data that LTP is going to fetch with pre-filters like “Suggested Bid” (or Cost per Click [CPC], i.e. the amount of money an advertiser is willing to pay for a click on their AdWords ad that is targeting that specific keyword), “Local Search Volume” (average number of monthly searches for a specific keyword), “Advertiser Competition” (the amount of advertisers competing for a specific keyword) and “Number (of) Words” (very important when you’re trying to find long-tail keywords).
For a long time, I wanted to develop a tool for content marketers that would assist in the process of coming up with blog ideas and subjects. Upon researching developers for this concept I had, I stumbled across  Long Tail Pro, and realized instead of developing a tool myself for fellow bloggers and content marketers, I would throw my support behind this one.
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.