BookWalker is a business that has been sending out lots of emails to authors, offering to help them market their books.
The price? A mere $2939.00.
If you are even considering spending that kind of money you definitely need to do your due diligence. Fortunately, the excellent "Writer Beware" blog has done some of it for you. Here's a small sample, about the BookWalker website:
"Similarly, there’s nothing to back up the promotion and relationship claims: no client names, no examples of successful PR campaigns, no mention of who the partner literary agents, collaborating editors, etc. actually are."
That alone should be enough to set off alarm bells, and there's plenty more.
Based on the information in the Writer Beware look at BookWalker, my advice is, don't walk--run!