Coke isn't comparable to boots in this case. Unlike boots, there is relatively little difference in price or quality in colas and the price is low enough that almost everyone can afford them. On the other hand, there is a dramatic difference in price and quality in footwear.

Sam's Cola is $8.54 for a 24 pack while Coca-Cola is $13.48. (Both prices taken from Walmart).

Cheap work boots are $30 at Walmart while Red Wing Super Soles are $250 while Iron Rangers are $350.