Posts like this always baffle me. How will knowing what someone else makes, help you?
Black hat, you can make $5,000k + what that comes a lot of hassle and headache. Of course you can make more, but your exposure and risk increases exponentially.
Doing things Right you can make $15,000 + with that comes less hassle and headache, and more strategy and logistics. This is pretty scaleable, as there is always new product lines to get into.
I make a lot of money on ebay, 100% legit.
In regards to the FVF , you need to factor in that variable expense when sourcing products. My rule of thumb is simple, if my margins are so tight that I'm worried about paypal fees and ebay fees then it's not worth selling that item. There are plenty of items with healthy margins out there.