Sale #1:

http://www.tf2outpost.com/trade/25950176

Sold for 40 keys

Seller:

http://backpack.tf/profiles/76561198074924284?time=1431586800 (May 14th)

http://backpack.tf/profiles/76561198074924284?time=1431673200 (May 15th)

Buyer:

http://backpack.tf/profiles/76561198091979796?time=1431586800 (May 14th)

http://backpack.tf/profiles/76561198091979796?time=1431673200 (May 15th)

Inventory Screenshot:

http://i.imgur.com/ttX4AoM.png http://i.imgur.com/nxZ5YYp.png (Credit to mb)

Sale #2:

http://www.tf2outpost.com/trade/25740864

Sold with Holiday Headcase (12) + Pro Carbonado Sticky (8) + Spec Gold Wrench (4) for Ghastly Ghosts Jr. Chieftain's Challenge (35)

Seller:

http://backpack.tf/profiles/76561198103514638?time=1427958000 (April 2nd)

http://backpack.tf/profiles/76561198103514638?time=1429513200 (April 20th)

Buyer:

http://backpack.tf/profiles/76561198074924284?time=1429426800 (April 19th)

http://backpack.tf/profiles/76561198074924284?time=1429513200 (April 20th)

Items given: http://i.imgur.com/bAy4r6T.png

35 - (12 + 8 + 4) = 11 keys? Probably not the most usable sale. It's a little old to use now, also.