First off, very few sellers are going to be personal shoppers for 10%. Gosh, gas alone would eat up that 10%, not taking fees, time and work involved in shopping, listing, dealing with Q&As, etc.
Consignment shops take from 30%-60% of the selling price and personal shoppers double and triple cost for their services!
As for your comments about the markup on Coach Peyton domed satchels, what stopped you from buying one (or more) at the outlets for about $65? To play devil's advocate, you snooze, you lose. (And I don't have any of that bag, don't sell on ebay or posh and I have no horse in this particular race.)
I realize this has been discussed many times over many years and on many brands so without going into members' opinions on that, I just want to comment on your use of "ethics."
There's absolutely nothing unethical about listing items at inflated prices. It's the basis of capitalism; items are worth what a willing buyer will pay. And if it doesn't sell at a price the seller lists for, they either reduce the price, sit on the item and it never sells or they wait for the right buyer.
But IMO, "ethics" has nothing to do with selling and the prices items are listed for.
As an example, I saw identical Uggs boots (same style, size and color) this winter at both TJ Maxx,
Nordstrom Rack and
Nordstrom (mall store). At TJ's, they were $129.99, at the Rack they were $199 and at the mall store they were around $300. (I don't recall the exact prices since it was a few months ago.) Are Nordies or the Rack less ethical than TJ Maxx? Is Nordstrom at the mall less ethical than its Rack counterpart?