A few reasons I have for keeping Auctiva:
**free scheduling (which allows me to make my auctions during my free time and let them launch at an ideal time)
**cool templates and layouts of my images (fee-bay charges for that too)
**Auctiva saves all my listings and images (ebay deletes after a certain amount of time-do they even keep the images on file for use later?)
**super sizing of images, which I take full advantage of when I sell things that I need to get close-ups of for the details (like my collectibles)
**I like being able to click a few buttons and make a whole new listing from a saved one.
In the end, my savings really add up on the scheduling fees, so having Auctiva pays for itself (and actually saves me money than if I listed directly on feebay.) and all the other benefits I get are considered "added" bonuses (like the image hosting and super sized images.)
If you don't like to schedule your listings to launch at a specific time, or have a nice template, or have your information saved after your auctions end, then you probably wouldn't need Auctiva. It just makes my life a lot easier, and for 10 bucks a month it is an easy choice for me to make.