About 12 years ago when I was in the IT networking game, I also ran an eBay based bookstore selling mainly Cisco Press items.
It was ok, but only because I was getting the titles at ÂŁ10 each and selling them for ÂŁ30+ with some going for as much as ÂŁ70.
Unfortunately, eBay have gotten increasingly greedy almost to the point that unless you have excellent margins, you're on a loser to begin with. 10% off the bat and then another 4% going to Paypal, couple that with them imposing limits on what you can charge for postage and it begins to become a real pain in the neck.
And unless you ship everything via a tracked service, you run the risk of getting ripped off by punters who receive the goods and say they haven't. It's then that you'll realise Paypal and eBay care more about the customer than they do about you and your business.
As far as I'm concerned, eBay is now just an outlet for a load of toot from China. Personally, I would not trust the authenticity of anything for sale on there.
That aside, you might find you are better off having an e-commerce website, and putting your energies into that. If so, have a look at this software:
eCommerce Software | CubeCart
Its cheap and easily tailored. Whatever you decide, I wish you good luck.
Cheers