I have 2 kindle books at $4.99 and one at $2.99.
I haven't really experiment with price myself but from spending time on various kindle forums, it seems that the only way to really determine what pricing has the best profits is to simply test. For example, if your book is $4.99 and you sell 10 copies, great, you get like $2 commission for each sale. But some people find if they price it at $0.99 they'll get 100 sales. Just have to test it. I should take my own advice.
One thing you can do to basically double your profits is to go on ACX.com and hire a narrator and do a royalty split with him/her to professionally narrate your audiobook version. It costs nothing out of pocket and my audiobook sales are now outstripping my eBook sales and this is non-fiction, which is known to sell quite a bit worse than fiction.
Createspace has made me a few bucks but I haven't found it to be anywhere near as lucrative as kindle and ACX.
Make sure to get a great cover and fill out the entire description (for SEO purposes). Also do the 5 day free promo once you launch and get as many reviews as you can out of the gate, even if it means hitting up friends and family on Facebook. It makes a difference.
Good luck and hit me up if you have any questions.