No, of course not. If the current bidding price is 10% or 20% above the market, why the hell would a sane person bid even more, rather than just buying directly from the market?
2 reasons, First you can't buy 50K straight from the market as the prices will increase by 10% even by buying 5K bitcoins.
And you will have to trust a large amount with a third party while doing so.
This is not strictly true, 5k if you was to buy all at once maybe, but no real traders i know do that very often what would happen is multiple buy orders across multiple exchanges and people would dump into them within a couple of days no problem.
Now the same can be said for those selling from the buyers! I would argue if i was a buyer go and try sell 50k on exchanges and see what price you get
There is very little chance they paid over market more like under market value.