Item Snapshot made
Classifieds
45 keys
Haunted Beep Man 2 Gifted A Mann's Mint 5798524592 3132876089100 keys
Haunted Beep Man 8 Gifted A Color Similar to Slate spells 8035564289 312074116860 keys
Haunted Beep Man 92 Gifted spells 7540190234 315355028739 keys
Haunted Beep Man 61 Timed Drop Radigan Conagher Brown 8194745158 3126550726
Marketplace.tf sales last month
1 @ 63.71$
63.71 : 1.82 = 35 keys
https://manic.tf/keyprice/?at=2019-10-03
1 @ 64.35$
64.35 : 1.82 = 35 keys (35.36)
https://manic.tf/keyprice/?at=2019-10-04
Steam community market last week
1 @ 70.24€
70.24 : 2.15 = 33 keys (32.66)
https://gyazo.com/604989c1f56ffcaea604547ff769a69a
1 @ 71.16€
71.16 : 2.15 = 33 keys (33.09)
https://gyazo.com/1414902ca67168551b94a0cf3e6ceb4e
1 @ 108.95€
Thanks to Shuffle Spy for the additional info!
https://steamcommunity.com/market/listings/440/Strange%20Haunted%20Beep%20Man - Sales at $58.08, $48.04, $48, $64.88, $64.17, and $65.40
Those are the sales from 10/14 onwards, and they convert to 25 Keys, 20 Keys, 20 Keys, 28 Keys, 28 Keys, and 27 Keys
https://marketplace.tf/items/tf2/30509;13;strange - 2 buy order sales.
https://imgur.com/a/beuOGLq - Given buyers at 23 and 24 Keys, I'd exclude 25 Keys. 27 - 35 should work, though.
https://backpack.tf/u/76561198044195191
https://backpack.tf/u/76561197963500354
https://backpack.tf/u/76561198064658655