Equinux (http://www.equinux.com) has released iSale 5.6.3, the latest version of the eBay auction tool. The new version works more reliably with eBay Motors
iSale costs US$39.95, though version 5.6.3 is a free update for registered users of version 5.x. Upgrades from previous versions to 5.x are $19.95.
iSale is Universal Binary so runs natively on both PowerPC and Intel Macs. It requires Mac OS X 10.4 or higher.