Jim,
You are really shortchanging yourself. I've seen your shots and they are worth much more than the rates you mentioned.
I understand if your intent is not necessarily to make money off of these but you should at least fairly reimburse yourself for your time and materials. Naturally there is a balance to be found, because if you price yourself too low, you end up selling a lot but losing more money with each sale. Price yourself too high and you don't make enough to cover expenses (such as track entry fees, gas, lunch, hotels, etc, not to mention amoritizing your equipment investments) or PAY YOURSELF for your time (both behind the camera and in front of the computer).
I sent you a PM with a reply to your PM on this same issue but it's just a WAG. I'm struggling with figuring these issues for myself. I recently picked up
Best Business Practices for Photographers (2nd Ed). The author spoke at a couple of events at FotoWeekDC and I was very impressed.
Mike