I was feeling frisky yesterday morning and took the plunge. Seeing the keyword was one of those 'huh, what?' type moments that several people have described.
Looked around, ran it through some of my pro tools (yeah basically long tail pro) and I thought 'wheeeellll... that IS a pretty legit low competition keyword'. Checked out the top 10. There's only one page there that has any text to speak of.
Don't really want to spend the rest of my life writing about that topic but I knew if I knocked out a thousand relevant words I'd rank pretty well. Well 2,000 words later and I'm all set to dominate this little niche and hoover up whatever money is sloshing around.
I'm ranking on page 6 already, which might be meaningless or might be proof that this niche is ripe for the taking.
I feel like I could have found the keyword myself if I'd gone through tons and tons of Amazon sections and done loads and loads of messing about in LTP. For me it was worth the cost of the service to save that time.