REA increasing their BP and making other changes

[piecesofthegame]

I find all the discussion about BP a lot like going to your cell phone provider’s store to get a new phone or change your plan…ridiculously confusing! They are literally in the business of running rings around you with the numbers. It’s what they are paid to do.
As mentioned by many previously, they can charge whatever they want for BP, it’s not going to change what I’m willing to pay in the end. I have a figure in mind, I make my bids and and mentally add the % to my bid, and when it’s over my bid, see ya next time.

Now here’s what I DON’T understand. Why are reputable companies who sell using ebay (Probstein, 4 Corners), not viewed as a better option for a consigner than large auction houses? The major ones using eBay offer 95% of the sale price on items selling over $1000. So do the math…

$5000 card through auction house
$4000 bid + 23%=$4920.Result to consigners is $4K IF…IF they have 0% consignment fee. That’s best case scenario.

$5000 card on eBay through Probstein, 4 Corners, etc
$4920 winning bid (to keep all things equal). Result to consigner after 5% fee=$4674.
This seems like a No-Brainer for a consigner. What am I missing? I realize when we get into 5 digit, 6 digit, and 7 digit cards, no one will throw them up on eBay and hope for the best. But for the $1000-$10000 cards, I don’t understand why it’s not considered as an option by more consigners.