I am completing a business plan. I am looking for research or reports
for free or for fee, that depicts "true" net profit of the average
ebay seller. You hear adds saying I "made" $10,000 on ebay. Most of
the time this is gross revenue or sales. I want to know on average,
what the successful seller makes. I want to know as % of revenue the
average successful ebay seller makes (net profit) 10% of revenue or 12%
of revenue.
I can imagine what those who don't sell well loose.

I would be interested to know this as well but is it really possible
to get any information even partially accurate? In order to determine
the average PROFIT one would have to know how much each item cost the
seller.

You are correct, however, I was hoping some market research firm did
some type of analysis that tries to estimate seller costs to arrive at
net profits. I'm actually skilled at doing this analysis with the
proper data. I am looking for ball park, estimates. Is successful
seller net profit as a percentage of revenue in the following ranges
0-10%, 10%-25%,or 25% to 50%. Not likely in higher tier three, but
knowing tier one vs tier two is critical to my research.

Maybe some market research firm has surveyed sellers (if their honest)
about their real earnings.

I could easily look up pure "e-tailers" who are publically traded to
get an idea. But their base economics are typically different, so it
may not be an apples & apples comparison to the ebay seller. I
actually don't have time to do this, hence my post on Google answers.

Deeply appreciate the comment.