If adding to your "buying keywords" vocabulary is of interest to you, then you might be interested in taking a peek at this book. I just discovered it myself. 

I have no vested interest in it. Just trying to share something of value that can perhaps help your marketing endeavors.

It's a book called Words That Sell by Richard Bayan, from Google Books.

Chapters and keyword phrases are online, and you can read them here.

Hope it inspires you!