Using sales for the last 3 months, the item was sold for:

$55.56 (mp.tf)

$79.99 (mp.tf)

$105.46 (SCM)

mp.tf:

marketplace.tf/items/tf2/30416;5;u89

Nov 18th, $55.56

keys at the time averaged $1.72 on mp.tf, so 55.56/1.72 = ~32 keys

Dec 24th, $79.99

keys at the time averaged $2.09 on mp.tf, so 79.99/2.09 = ~38 keys

SCM:

backpack.tf/item/4692469768

The hat becomes tradable after Feb. 4th, so that means that the hat was bought on Jan 28th through the SCM (prnt.sc/xttilq)

The SCM chart (here shows that on Jan. 28th, a hat was sold for $105.46

Taking 15% off in account of Steam's transaction fee, it equals $89.64

Keys at the time averaged $2.45 on SCM, so 89.64/2.45 = ~37 keys

Sales

32, 38, 37

Taking 32-38 keys

If I missed any sales let me know