My hubby is a programmer, so he has designed a selling website that uses a paypal checkout system. Once it becomes more popular, we will probably get a merchants license for credit card purchases.
We created it to sell items from about a dozen different sellers at once, so now have a lively little hub.
Your main problem is getting traffic into your site, thats what ebay's big seller is...where else can you get thousands and thousands of people browsing at any one second?
So, I hit a couple of forums that target the audiences I want to sell to.
Its fun, my any website/forum is such hard work in the early days.
You need to ensure you hit the search engines and get your site in there, then you will get some traffic.