There is a lot wrong here, especially for someone with a black belt.

You need to ensure the item you're trying to price is visible in the compare links you're linking as proof, as such you miss out on potential sales (such as sale 2)

For example:

Better view of the 60 sale from sale 1 - https://backpack.tf/profiles/76561198232041512#!/compare/1643760000/1643932800

Sale 2 is 50 keys https://backpack.tf/profiles/76561198022330462#!/compare/1644278400/1644364800

Sale 3 wasn't a quicksell, it took from 8th Feb to the 5th Apr to sell. Can't trace what it actually sold for though.

Then it quicksold, for 35 keys, on the same day it was purchased (5th Apr)

There's also a new quickbuyer for 35 keys - https://gyazo.com/ef77ee544c5f4c119f17d441d697f573

35 won't be usable here