During the 1800's there were endless arguments slave vs free labor. Slaveholders argued that slaves, in effect, had cradle to the grave food, clothing & lodging. This was compared with the degraded lives of workers in free labor states who were chucked out into the gutter when it suited their employers.
It was, in fact, seriously argued by the loudest advocates of slave labor that it is God's intention that a race of masters was required to keep the common folk in good order. God did not want there to be free labor. After all, not a single word in the Bible condemns slavery as a sin, quite the contrary. Slaveholders were, doing their slaves a favor by looking after them.
Of course, the question here is about dollars & cents. Studies have shown that while the invention of the cotton gin fueled a multifold increase in the cash flow of cotton plantations, the economic underpinnings of the slave/plantation model was failing. All across the upper tier of slave states by 1860, slaveholding had ceased to pay. In Tennessee, the 1850 to 1860 census showed a distinct downward trend All you have to do is look at the debt ridden mess that Robert E. Lee was stuck with by his father in law to understand just how desperate the financial condition of many slaveholders really was. The only reason Lee was available to supervise John Brown's capture was his leave of absence from the army to set the family finances aright.
It costs a lot of money to raise a child to a working age. Even with the best of care, the little tykes will just up & die on you. One of my greatgreatgranddads inherited a 1/3 share in a woman & two toddlers. This is an example of one of the economic traps of slaveholding. All your money is tied up in slaves. All the rail roads in America combined were worth considerably less than the 4.000,000 slaves. He also inherited a saddle, $50 & a slave named Moses who had appeared in two previous wills. My ancestor was a school teacher with no money. Moses must have been 80 years old, so had to be provided for. The only way to monitise the woman & toddler was to sell her. That presented a problem.
Toddlers were of course, wort a few hundred dollars. However, if sold separately from their mothers, human nature caused problems. The toddlers tended to pine away. Their mothers, naturally suffered deep depression & tried to run away. None of that was good for business. Stripping her naked, staking her out spread eagle on the ground & beating her with a whip was the common & ordinary way to motivate her to attend to her duties had its own downside. I do not know what happened in my family example. However, there is a probable answer.
"Families Will Be Sold As One Lot." Appears on slave sale hand bills. Commendablely, this sounds humane. Ma, Pa & all the grand chillens going off together. Unfortunately, that is not what the marketing term means. Mothers, babies & toddlers would be sold as lots is the actual meaning. Since my ancestor never personally owned any slaves, Moses must have died, & the little family sold. Exactly how to equate grandpa's monetizing of that one third share with, say the Irish woman whose child became his daughter in law escapes me.
In the rice & Deep South plantations it was the recommended model was to purchase teens & rotate your stock on seven year intervals. There is nothing caring or kind in slaveholding. Household slave women who were too old or whatever to work were set on the public square with a sign reading, "$50.00 or best offer." Hung around their necks.
The northern tier of slave states greatest cash crop was the sale of durplus labor. A regular set of stages moved the surplus southward to the Forks in the Road for sale. So, trying to equate the value of a man day of labor in a slave system is almost impossible to equate with that of a master craftsman, journeyman or laborer. One thing is certain, slavery was a profligate waste of talent. All genius or creativity was utterly & completely wasted. That was the true bankruptcy of slaveholding.