no way is this worth 42 keys.

sale 1: sold for 25 keys+s.prof ks degreaser

http://backpack.tf/profiles/76561198065057392?time=1430204400

http://backpack.tf/profiles/76561198065057392?time=1430290800

12*0.9=10.8 rounding to 11

25+11=36

sale 2: sold for miami nights attendant[25 keys via mini]

http://backpack.tf/profiles/76561198083612473?time=1432191600

http://backpack.tf/profiles/76561198083612473?time=1432278000

sale 3: sold with a key for kaw metal drill hat[16 keys via mini]

http://backpack.tf/profiles/76561198160624771?time=1431932400

http://backpack.tf/profiles/76561198160624771?time=1432018800

16-1=15

sale 4: sold for kaw slope scopers[16 keys via mini]+ a key

http://backpack.tf/profiles/76561198043835192?time=1431414000

http://backpack.tf/profiles/76561198043835192?time=1431673200

16+1=17

mini on attendant: sold for steaming rack[27.5 keys]

http://backpack.tf/profiles/76561198092378907?time=1432364400

http://backpack.tf/profiles/76561198092378907?time=1432450800

27.5*0.9=24.75 rounding to 25

mini on metal drill: sold for peace sign batters helmet[18 keys via mini]

http://backpack.tf/profiles/76561198125021096?time=1431932400

http://backpack.tf/profiles/76561198125021096?time=1432018800

drill history: http://backpack.tf/item/2193638332

18*0.9=16.2 rounding to 16

mini on batters helmet: seller at 18 keys

http://www.tf2outpost.com/trade/26158882

mini on slope scopers: sold for kaw metal drill hat[16 keys via mini]

http://backpack.tf/profiles/76561198043835192?time=1431759600

http://backpack.tf/profiles/76561198043835192?time=1431846000

mini on degreaser: 12 keys

http://gyazo.com/df37f126aa008abe15fec64505279fe8.png

sales at 15, 17, 25, and 36. calling 25 and 36 outliers.

taking a final price of 15-17 keys. seems about right for this hat+effect.