There is no need to spend money on keyword tools when you have everything available to you free of charge.

First, use Google's free keyword tool to generate keywords for your campaign:

https://adwords.google.com/select/KeywordToolExternal

Next, use the typo generator:
http://tools.seobook.com/spelling/keywords-typos.cgi

Yahoo! Search marketing is an untapped resource. We suggest opening up an account and begin building your campaign. We have found that clicks are significantly cheaper using Yahoo! search as compared to using Google Adwords. Check them out at:

http://searchmarketing.yahoo.com