Ignorance can be excusable, but this fails on common sense grounds. It may be true that plantation owners need more helpers for winter (although considering they tended to live in the south, it is probably false). However, when you have a limited supply and a higher demand, do you give a discount?
This is also factually wrong. See http://money.cnn.com/2014/11/28/news/black-friday-history/index.html, for example.