Yasuba proved this; Fogel and Engerman proved this; we already have preliminary evidence from a massive study of NO slave prices from data sources that no one has seen that confirm this.
Again, you might find one or two---you can still find economists who think that FDR didn't spend enough, and you certainly know the "on the other hand" comment about RR and economists---but the vast majority (see the discussion in Atack and Passell, "New Economic View of American History") does not support your view.
The notion that you can sell off a scarce good---no matter what that good's function---and NOT drive up prices on all remaining similar goods defies economic logic. But when those goods are inherently imbued with power/oppression, then it isn't even close. Slave labor was very marginally profitable over free labor, unprofitable compared to manufacturing, but tremendously profitable as a source of power, especially when subsidized by the state. And even Weiss's paper does not take into account the hidden value of government subsidies to slavery when determining profitability.
Which contention on your part (cite your evidentiary sources, please) doesn't account for why Compensated Emancipation was succesful in every other country where it was tried.
Here's why it was successful: once slave-holders were paid a market rate of compensation for their slaves, they took the money and shut up about it. Which means that you can argue all you want about the alleged "power-vs-profit" aspect of slavery in theory; but in practice, slave-holders were content to take the money.