This suggestion is an icky suggestion

Sale 1

[No OP Trade] Sold for 19 keys

X = 19

Keys https://gyazo.com/8d9f4d971de67664920af521542d48aa http://backpack.tf/profiles/76561198039768476?time=1442559600&compare=1442646000

Festiv http://backpack.tf/item/3206932530

Sale 2

http://backpack.tf/profiles/76561198108295348?time=1446188400&compare=1446361200 Probably sold for for 19, 14 of the keys probably used to by an OF Pickelhaube, but only 9 can be seen http://backpack.tf/profiles/76561198024700553?time=1446102000&compare=1446188400

Sale 3

[No OP Trade] Sold for Stormy Festivizer + 10 keys

X = 17.5*0.9 + 10

X = 26

Keys + Stormy http://backpack.tf/item/1177517217 http://backpack.tf/profiles/76561198034095893?time=1442991600&compare=1442905200

Miami http://backpack.tf/item/2176377864

Mini for Stormy

http://backpack.tf/vote/id/56615db6b98d88471be94b40 17.5 keys, using 17.5

Sale 4

http://backpack.tf/profiles/76561198068064085?time=1442818800&compare=1442732400 Bulk sale with Aussie Medi Gun for Twatt Brainiac's + 3 keys

Sale 5

http://backpack.tf/profiles/76561198123596910?time=1448352000&compare=1448265600 Bulk Sale for DP Peacenick's

Sale 6

http://backpack.tf/profiles/76561198096209568?time=1448179200&compare=1448265600 Sold for like 13 in sweets, Outlier

Sale 7

http://backpack.tf/profiles/76561198068379636?time=1444114800&compare=1444201200 Sold for KaW Tavish + Planets Engi Cap + 3 keys

No mini available for Tavish so I cannot use it.

Seller

http://www.tf2outpost.com/trade/27436212 B/O of 20, unsold for 2 weeks, declaring the two other sales (Not the pure one) an outlier, I guess