They used to charge €1/year. It seemed extremely little, but I did the math once and it worked out (around 2015, when they already had about as much market share as they do now in the Netherlands), including things like wages. There was even money left for a Ferrari for every employee. This is assuming that they actually charge everyone by the way, which they weren't (I don't understand why -- it seems cheap enough that even people in a developing countries could afford it).

I too would gladly pay (anything reasonable) if it meant they'd split off from Facebook and become in dependent again.