This is not true.
The money price of any slave, would never go above the money value of the labor which could be extracted from that slave. A slave-holder would not pay a million dollars for a slave which would only deliver $20,000 in labor value over his lifetime. This "upward bound" on the money value of each slave is one of the reasons why Compensated Emancipation worked in other slave-holding countries, and why every slave-holding Western nation except the USA was able to end slavery without a war.
Ergo, in principle, Ron Paul is right.
Even a very generous Compensated Emancipation program would have cost the USA half the money, none of the economic damage, and none of the 600,000 dead.
Absolutely and totally wrong. Every economist who has studied this has concluded that slaves had an inherent property value far, far above their labor value. This is not in debate among the economic historians who have written on this. Only goofballs like DiLorenzo still try to make this silly argument.