actually, i dont quite need a toolbar, just a reminder.
in Windows, when you install the eBay toolbar, it'll install a system tray icon that notify you of items that you are watching or bidding on, that are ending in 10 minutes.
i've missed quite a few items since i used OSX, because of no notification
Some are shareware, some are free. jBidWatcher is free and looks quite full-featured. I use the eBayAddict widget (also free) from time to time.
A really handy AppleScript is eBaytoiCal, which will create a reminder with alarm in iCal at a set time before the auction ends.
I take it you're a recent switcher? Get in the habit of looking for widgets to replace your Windows toolbars. They'll use fewer resources and won't install themselves (and heaven knows what spyware) in every corner of your system.