Accidental counter (didn't notice until I'd already typed most of it out, sorry.) Ty to cashew for the first 4 sales.

Sale 1

Sold for 42 keys and ~1 key sweets = 43 keys

Seller before: http://backpack.tf/profiles/76561198064036825?time=1429426800 (April 19th)

Seller after: http://backpack.tf/profiles/76561198064036825?time=1429599600 (April 21st)

Sale 2

Sold for kill-a-watt galvanized gibus (53) = 53 * 0.9 = 48 keys

Seller before: http://backpack.tf/profiles/76561198163179642?time=1429599600 (April 21st)

Seller after: http://backpack.tf/profiles/76561198163179642?time=1429686000 (April 22nd)

Sale 3

Sold for pe spartan (45-53) = 49 * 0.9 = 44 keys

Seller before: http://backpack.tf/profiles/76561198092483485?time=1425110400 (February 28th)

Seller after: http://backpack.tf/profiles/76561198092483485?time=1425196800 (March 1st)

Sale 4

Sold for scorching timeless topper (25-29) = 27 * 0.9 = 24 keys - quicksell/outlier

Seller before: http://backpack.tf/profiles/76561198072837943?time=1424505600 (February 21st)

Seller after: http://backpack.tf/profiles/76561198072837943?time=1424592000 (February 22nd)

Sale 5

Sold for 3 buds (12 keys) pure = 36 keys

http://www.tf2outpost.com/trade/24594778 - seems like a quicksell, trade wasn't up long

Seller before: http://backpack.tf/profiles/76561198067889005?time=1424851200 (February 25th)

Seller after; http://backpack.tf/profiles/76561198067889005?time=1424937600 (February 26th)

Mini for kaw gibus:

Sold for pro ks scatter (39-46) and 3 buds (5.5) = (42.5 + 16.5) * 0.9 = 53 keys

Buyer before: http://backpack.tf/profiles/76561198103187983?time=1429426800 (April 19th)

Buyer after: http://backpack.tf/profiles/76561198103187983?time=1429599600 (April 21st)

Micro for pro ks scatter:

Average buyer pays ~$110

Average seller receives ~$93.50

Scm key price ~$2.40

110/2.40 = 46 keys

93.50/2.40 = 39 keys

Range = 39-46 keys

Found a few other recent sales but they involved spotty backpack histories or lots of hats in one trade, so this should be ok.