If you're looking for an alternative to the costly apps out there, you can try using the Batch Export Utility developed by Lvid Instruments. It works on par with Compressor and its ease of use blows Cleaner out of the water. Mac only. Available free for download at: http://lividinstruments.com/products/beu.html
If you haven't done so already, you should see if this can be helpful in the Mac section http://forums.afterdawn.com/forum_view.cfm/56