I use QB2005. If I was only doing ebay, dunno if i'd bother using it. It can result in alot of extra work. (putting items into inventory, etc. You can do non-inventory sales, just depends on what data you want to track and how you want to track it)
What I like about it is that can create professional looking receipts and can email the receipts to customers (when item is shipping out, i email the receipt to them with a 'your item has shipped' note)
And, of course, it's very handy for generating reports of income and expenses. But, like i said, it results in lots of extra work. So, it really just depends on what you want and need.
BTW, there's other versions of QBs that is cheaper than the retail version. Think Academic version
Academic version is about 50% off.
Of course, you have to qualify for academic, which how strict they are will vary from vendor to vendor. BTW, I've even seen academic versions of software at sams club.
Also, there's tons of fake copies of QB on ebay.