Using the past month.

bot.tf stats:

https://bot.tf/stats/item?def=30614&q=5&ef=Skill+Gotten+Gains&craft=1&aus=0&ks=0

Past 30 days:

1x 3.00 keys

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Marketplace.tf stats:

https://marketplace.tf/items/30614;5;u3007

Past 30 days:

1x $17.59 ($17.59 / $1.77 = ~10 keys)

1x $7.50 ($7.50 / $1.79 = ~4 keys)

1x $7.95 ($7.95 / $1.79 = ~4.5 keys)

1x $7.35 ($7.35 / $1.80 = ~4 keys)

1x $7.28 ($7.28 / $1.79 = ~4 keys)

Sales:

3, 4, 4, 4, 4.5, 10. Going with 3 - 4 keys.