I don't have info on it, but 20/20, Dateline, etc have done little special things on people that are making lots of money off of it.
There is a convention in Vegas every year specifically for the people that use EBay for their sole means of making money.
It is to the point now where EBay is considering (haven't looked in a bit, but perhaps they actually do it now) providing health care plans for people that make their living selling stuff on EBay.
Most of the examples I have seen have been fashion people, and antiques. The cars that are sold, at least the high end cars from dealers, are actually only really on there to generate views - they aren't usually actually sold on EBay - advertising of sorts.
The fashion people would have connections at stores of when clothes were going to be gotten rid of and would go buy out a store and then sell the stuff on EBay.
One family had the mom doing the books and ads, and the daughter's hot bod was used to model the clothes. The dad had the connections to get the merchandise.
They were doing well enough that they bought the house next to them and used that as their warehouse/office for EBay stuff.