Sale 1:

https://backpack.tf/profiles/76561198131633162#!/compare/1588809600/1588896000

https://backpack.tf/profiles/76561198043598087#!/compare/1588723200/1588896000

Sold for Neutron Star Counterfeit Billycock (22) + 10 Keys

= 32 Keys.

Sale 2:

https://backpack.tf/profiles/76561198422586577#!/compare/1593734400/1593907200

https://backpack.tf/profiles/76561198137909800#!/compare/1593734400/1593820800

Bulk / Untrace / QS

Sale 3:

https://backpack.tf/profiles/76561198026526425#!/compare/1591228800/1591315200

https://backpack.tf/profiles/76561198203330566#!/compare/1591228800/1591488000

Untrace.

Marketplace.tf: https://marketplace.tf/items/tf2/31045;5;u9

Sale 4:

Jun 16 - $41.23 / $1.98 = 20.82 keys, No B/O

= 21 Keys.

Sale 5:

Jul 1 - $39.5 / $2.02 = 19.55 keys, No B/O

= 20 Keys.

Sale 6:

Jul 16 - $63 / $1.98 = 31.82 keys, No B/O

= 32 Keys.

Sales: 20, 21, 32, 32

Going with 20-32 keys.