The price an enslaved person fetched at auction was determined by their physical condition, the island they’d landed on and how many other slave ships were in that particular port at the same time.
Those who were not sold at auction were sold for a fixed price and were placed in a scramble where plantation owners could grab as many enslaved people as they could.
Any of the enslaved who were left over at the end were usually left to die on the docks or were bought by doctors who would nurse them back to health then sell them on for a profit.