Right.....because they wouldn't have used some of the money to get more slaves from outside sources.
When the Constitution was adopted and the Union formed, slavery existed in practically all the States; and it is claimed by the Southern people that its disappearance from the Northern and its development in the Southern States is due to climatic conditions and industrial exigencies rather than to the existence or absence of great moral ideas.
As for the South, it is enough to say that perhaps eighty per cent. of her armies were neither slave-holders, nor had the remotest interest in the institution. No other proof, however, is needed than the undeniable fact that at any period of the war from its beginning to near its close the South could have saved slavery by simply laying down its arms and returning to the Union.
The importation of new slaves to the Southern states actually ended around 1820.
The British Parliament outlawed the African slave trade about 1815.
The British Navy sealed off North American trade by about 1820.
The slave trade to South America and the Caribbean would continue for several more decades, but much reduced in numbers.
Almost all “new” slaves in the South after 1820 were people born into slavery.
If Lincoln had made the offer to buy all slaves, then followed up with a propaganda blitz about how slavery crushed the wages for unskilled white Southerners, there's a chance the Civil War could have been avoided.
The main problem was what to do with the newly free slaves.
Southerners didn't want them wandering around the South.
Northerners were almost as racist as Southerners, and would never have agreed to accept millions of free slaves.
Sending them back to Africa was just a political fantasy, as Liberia proved to be.
By the way, I have never bought into the whole “Preserve The Union” rationale that Lincoln used to begin hostilities.
I mean, updated to 2011, if California and New York City decided to secede, would you charge across an open field into canon fire to keep them here?
Not me, dude.
Take the slavery issue out of the Civil War, and there would have been no Civil War.