Provides links to price estimate tools from Google AdWords. That Google AdWords tool showed the necessary bid to rank #1 for 85% of queries, and roughly how much traffic you could expect AdWords to send you based on that bid price and ad position, though, as mentioned above, Google has obfuscated their data in their interface for everyone but longtime AdWords advertisers.
1) SEMrush - I believe that among all the 3rd party software, SEMrush has the largest keyword database. Their search volume data is pretty accurate and aligns with the Google keyword planner. Also, based on the type of content that needs to be produced (i.e. informational, transactional, etc.), one can utilize different filtering options available in it.
Long Tail Pro is a keyword research tool that helps you quickly find low competition keywords for your website. In particular, the tool is built for people doing SEO (search engine optimization) as opposed to people doing paid ads (Google Adwords PPC). I'm sure there are some advertisers that use the tool for paid ad keyword research, but the tool was built for SEO keyword research.