Here's a great resource to get your started in the muli-billion dollar online auction game!

Online auctions are a BIG business. The free software program from Everysoft allows you to run your own auction at your site.

Ideas
You can sell fitness books, equipment, videos, sporting goods or anything else at your auction. Here's the link:

http://www.everysoft.com/auction.html

Reality Check
A word of caution - don't try and compete with ebay. If you are not working on the Internet full-time, try to let first with ebay.com. They have millions of visitors and you can sell training manuals, equipment and books farily easily.

Here's a link to the fitness category:
http://listings.ebay.com/pool2/plistings/list/all/category15273/index.html?from=R4

Good luck!