going with sales from 1 April and on

Sale 1

https://backpack.tf/profiles/76561198857011965#!/compare/1557014400/1557273600

https://backpack.tf/profiles/76561198125791160#!/compare/1556928000/1557014400

bulk sale for a Cloud 9 Bombing run

Sale 2

https://backpack.tf/profiles/76561198134407457#!/compare/1556928000/1557014400

https://backpack.tf/profiles/76561198857011965#!/compare/1556841600/1557014400

Sold with 8 Keys for a Omniscient Orb Motif, bulk sale

Sale 3

https://backpack.tf/profiles/76561198104069164#!/compare/1556841600/1556928000

https://backpack.tf/profiles/76561198134407457#!/compare/1556841600/1556928000

untraceable

Sale 4

https://backpack.tf/profiles/76561198105637639#!/compare/1559088000/1559347200

https://backpack.tf/profiles/76561198311498888#!/compare/1559088000/1559174400

untraceable

Sale 5

https://backpack.tf/profiles/76561198311498888#!/compare/1558137600/1558224000

https://backpack.tf/profiles/76561198105637639#!/compare/1557360000/1558483200

untraceable

Sale 6

https://backpack.tf/profiles/76561198902573269#!/compare/1558137600/1558483200

https://backpack.tf/profiles/76561198876923029#!/compare/1558137600/1558224000

untraceable scammer sale

Sale 7

https://backpack.tf/profiles/76561198193075223#!/compare/1556150400/1559347200

https://backpack.tf/profiles/76561198902573269#!/compare/1557532800/1557619200

untraceable scammer sale

Sale 8

https://backpack.tf/profiles/76561198135388328#!/compare/1554422400/1554508800

https://backpack.tf/profiles/76561198340634356#!/compare/1554422400/1554508800

Scrap.tf sale

Sale 9

https://backpack.tf/profiles/76561198404553653#!/compare/1554163200/1554508800

https://backpack.tf/profiles/76561198135388328#!/compare/1554163200/1554249600

Scrap.tf sale

Sale 10

https://backpack.tf/profiles/76561198834678807#!/compare/1558137600/1558310400

https://backpack.tf/profiles/76561198880377562#!/compare/1558137600/1558224000

untraceable, sales before that were gambling

Sale 11

https://backpack.tf/profiles/76561198841279602#!/compare/1552953600/1553126400

https://backpack.tf/profiles/76561198112053907#!/compare/1552953600/1553385600

untraceable

Sale 12

https://backpack.tf/profiles/76561198082401774#!/compare/1552694400/1552780800

https://backpack.tf/profiles/76561198841279602#!/compare/1552694400/1552780800

Sold for 4 Keys + 2 ref.

Sale 13

https://backpack.tf/profiles/76561198369185032#!/compare/1555891200/1559260800

https://backpack.tf/profiles/76561198837007652#!/compare/1555804800/1555891200

untraceable

Sale 14

https://backpack.tf/profiles/76561198172729450#!/compare/1553990400/1555113600

https://backpack.tf/profiles/76561198375132279#!/compare/1555286400/1555632000

SCM sale

Sale 15

https://backpack.tf/profiles/76561198841279602#!/compare/1557532800/1557619200

https://backpack.tf/profiles/76561198113899098#!/compare/1557446400/1557619200

Sold for 4 Keys

Sale 16

https://backpack.tf/profiles/76561198811162245#!/compare/1555027200/1555113600

https://backpack.tf/profiles/76561198841279602#!/compare/1554940800/1555027200

untraceable

Sale 17

https://backpack.tf/profiles/76561198182213262#!/compare/1554422400/1554681600

https://backpack.tf/profiles/76561198811162245#!/compare/1554595200/1554940800

bulk for a Blizzardy Storm Towering Pillar of Hats

Sale 18

https://backpack.tf/profiles/76561198170493113#!/compare/1554768000/1554854400

https://backpack.tf/profiles/76561198048476913#!/compare/1554681600/1554768000

Sold for 4 Keys

Sale 19

https://backpack.tf/profiles/76561198305676157#!/compare/1554681600/1554768000

https://backpack.tf/profiles/76561198170493113#!/compare/1554595200/1554768000

Sold for 3 Keys + 34 ref

(3.5 Keys)

Sale 20

https://marketplace.tf/items/1108;5;u3005

Sold on the 17th April for 6.52$ (prob. was to buyorders)

Sold on the 17th May for 10$ (1.83)

= 5.46 Keys, rounding to 5.5 Keys.

Sold on the 26th May for 6.45$ (sold to buyorders)

Sold on the 29th May for 9.89$ (1.81)

= 5.46 Keys, rounding to 5.5 Keys.

Sales: 3.5, 4, 4, 4, 5.5, 5.5

https://gyazo.com/f3556d25f739a2cd0d91ac3553b190f2

Marketplace.tf sales on taunts are often high, with sellers multiple weeks old I'll exclude those sales.

Going with 3.5 - 4 according to Erik

That's it and that's all.