http://pages.ebay.com/help/sell/fees.html That will tell you what eBay charges sellers, we get the % of what eBay charges a seller.
I don't even know why people sell on EBay as a career...you're just better off using EBay as a starting source and eventually starting your own website. I say this from experience - EBay is legendary for Beginners Complete Crap if you know how the internet works
I still use eBay at times to sell but not like I use to. Got sick of all the fees and went towards affiliate marketing.