If you are an eBay seller, eBay is having a new free insertion listing promotion going live tomorrow, that is good from September 28, 2010 until January 7, 2011. During this period, insertion fees are waived for auction-style listings (regardless of auction starting price) on eBay US and Canada along with eBay Motors. There are limitations - up to 100 listings per person, and "no reserve" on the auction. They also have some other requirements and prerequisites, so be sure to read through the terms and conditions of this promotion.
Listing fees are only one of the various "feeBays", so be sure to factor that in your prices, but at least in this case, you only pay fees if your item sells or if you select any listing extras.
Unrelated, there are some upcoming changes in the US tax law that may affect people who sell a lot of items on eBay - changes that require record-keeping and form-filing with the IRS if you reach a certain threshold of transactions/revenue. Be sure to research them and get proper accounting/legal/tax advice as there seems to be plenty of confusion about these on the internets. We do not provide accounting/tax/legal advice!