https://marketplace.tf/items/17207;11;w1;pk207/

March 4, 2019 sold for $49.99 / 1.79 = 28

March 15, 2019 sold for $50.49 / 1.80 = 28

March 17, 2019 sold for $51.00 / 1.80 = 28

March 21, 2019 sold for $59.99 / 1.79 = 34

March 22, 2019 sold for $90.00 / 1.80 = 50

https://steamcommunity.com/market/listings/440/Strange%20Bonk%20Varnished%20War%20Paint%20%28Factory%20New%29

March 21 sold for $91.05 / 2.43 = 38 (2 sold this day)

March 22 sold for $91.61 / 2.43 = 38

https://backpack.tf/profiles/76561198158622105#!/compare/1550707200/1553817600

Bulk

In 2 days it sold 4 times for ~$90. I don't know.

50 keys is a high outlier.