Some adjustment to this suggestion.

Strange Bloom Buffed War Paint (Factory New)

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

Dividing by the average price of a key on that day.

1 sold on January 22nd:

$17.77/$2.21 = 8 keys

1 sold on January 28th:

$32.52/$2.20 = 14.8 keys

1 sold on January 30th:

$32.58/$2.15 = 15.2 keys

1 sold on January 31st:

$34.48/$2.14 = 16.1 keys

1 sold on February 7th:

$18.05/$2.15 = 8.4 keys

2 sold on February 12th:

$32.70/$2.18 = 15 keys

$33.61/$2.18 = 15.4 keys

1 sold on February 17th:

$23.83/$2.20 = 10.8 keys

1 sold on February 21st:

$20.22/$2.24 = 9 keys

3 recent March sales at ~10.5 keys

Outliers: 8 keys, 8.4 keys, and 9 keys.

Taking 10.5 - 16.1 keys as the range.

No recent Marketplace.tf purchases.