I was asked to help here, so here we go

Sales

http://backpack.tf/item/1148262538 - was bought for 43 keys pure + bills (6) + buck turner (2) = 43 + 8*0,9 = 50.2 = ~2.7 buds ( http://i.imgur.com/M1Hzaq2.png )

Outliers

http://www.tf2outpost.com/trade/20581544 - sold for beams ketche ~2.6*0,9 = ~2.35 + 5 keys (~0.3) = ~2.7 but we can't value this higher than 2.5 due to the B/O - so 2.5 is an outlier, not including it in the range

http://www.tf2outpost.com/trade/20510031 - QS

So why 2.5 is an outlier?

Because two current sellers within last week rejected 45 keys pure (~2.5) offers:

http://www.tf2outpost.com/trade/20186705

http://www.tf2outpost.com/trade/21083690

Beams ketche:

http://www.tf2outpost.com/trade/20382673 - sold for s f scatter ~2.7*0,9 = ~2.4 ( http://www.tf2outpost.com/trade/20402703 ) - original price used

http://www.tf2outpost.com/trade/20323878 - sold for peace tartan ~3.1*0,9 = ~2.8 ( http://www.tf2outpost.com/trade/20530018 )

http://www.tf2outpost.com/trade/20207187 - sold for scorching cone ~2.85*0,9 = ~2.6 ( http://www.tf2outpost.com/trade/20282238 )

Scorching dead cone:

http://www.tf2outpost.com/trade/18907552 - sold for GE tree ~5.1*0,9 = ~4.6 ( http://backpack.tf/profiles/76561198067738891?time=1397977200 | http://www.tf2outpost.com/trade/19340662 ) - outlier

http://www.tf2outpost.com/trade/19837395 - sold for 3 buds pure

http://www.tf2outpost.com/trade/20215386 - sold for beams rubber glove ~3*0,9 = ~2.7