Black Friday in Brazil is a fucking joke. As the saying goes "everything 50% OFF from double normal price".
What the stores do: they raise their prices by as much as 30 to 40% on the days preceding Black Friday, and then on the actual day, they sell the product at 20 to 50% OFF.
Worst case scenario, you're paying a 10% PREMIUM instead of getting a discount, and on BEST case scenario, they trick you into thinking you're getting 50% OFF, but instead, the real discount is closer to 5-20%.
The 20% best case scenario? It's easier to find a Unicorn than it is to actually find such a major discount.
In fact, following close examination of price trends over the last 30~90 days, i've found the best time to actually go and shop - at least for electronics - is 9~12 days PRIOR to Black Friday, as that's when i found the prices to be at their LOWEST.
Shit like that should be fucking illegal, stores that do this should be fined, and repeat offenders jailed.