You need to do considerable volume on ebay to start getting discounts. I reached the level once (i think then they did it over 3 month stretches) but it did not hold out.
Then they raised the fees to 10%, rather than their sliding scale, which, for the items i was selling, doubled my costs over night.
I then got an independant website, and, pretty much, used the ebay auctions to lead people to it.
I dont even bother with ebay any more. Its all too one sided. If youre a massive box shifter with high margins, then, im sure its great - high turnover means low fees, and if your markup is large enough, then loss through fraud is just another cost.
But, if youre low volume, high value, you only need one bad sale to stuff all the work from so many good sales.
It really depends what youre shifting - i think its ideal for drop shipping cheap imports, but for high quality things - well, look and see - how many ebay shops do you see doing much volume on that type of product? Not many...