I am definitely considering it, I have looked up what back-links some of the sites that I am competing with have, and the yahoo directory submission is the first one listed.
I wouldn't recommend doing this until you have done some free SEO marketing for your website. This way you can take a little bit of the profits you make and not have to shell out the whole $299 out of your pocket.
I like the post you put up BrainFreeze, that makes perfect sense. Obviously having good content is vital for getting repeat visitors, but having tons of back-links is what will get them into the door initially.
I use places such as: Using forums, submitting articles to the different directories, you can make Google and Yahoo groups and put link to your site there as well. Hope this helps a little.