Totaly agree with Jeff, CJ's book is packed with great ideas at a reasonable price.
Another that you should seriously consider
and one I would rank far better than two of those mentioned in your short list, is Success in Magic by Jim Snack. Rave reviews.
Modesty doesn't prevent my mentioning my own small contribution to field, MagicCoach 100. Details of this ebook and Jim's book available here. http://www.achieving.com.au/Illusion.htm
If you really want to throw yourself in at the deep end, check out the Marketing Forum run by The Dean, at http://www.thedean.net/forum/