Sellers:

http://www.tf2outpost.com/trade/29190677 - b/o: 21 keys (1 week)

http://www.tf2outpost.com/trade/29175820 - b/o: 25 keys (1 month)

http://www.tf2outpost.com/trade/29207054 - b/o: 25 keys (young)

Sold:

https://marketplace.tf/items/146;5;u61 - sold for $50.50 = 24 keys

http://www.tf2outpost.com/trade/28865764

http://backpack.tf/profiles/76561198072240925#!/compare/1491868800/1491955200 - sold for Tesla Coil Respectless Rubber Glove (26) + 6 keys = 25 keys b/o

http://backpack.tf/profiles/76561198080004660#!/compare/1491350400/1491436800 - sold with Circling Peace Sign Elf Esteem (16) for Green Energy Pyro's Beanie (28) = 12 keys (low)

http://backpack.tf/profiles/76561197994079316#!/compare/1491264000/1491350400

http://backpack.tf/profiles/76561198080004660#!/compare/1491264000/1491350400 - ?

http://backpack.tf/profiles/76561198050933686#!/compare/1493856000/1494115200

http://backpack.tf/profiles/76561198370415015#!/compare/1494028800/1494115200 - ?

http://backpack.tf/profiles/76561198050933686#!/compare/1491004800/1491264000 - ?

http://www.tf2outpost.com/trade/29069690

http://backpack.tf/profiles/76561198030385019#!/compare/1494806400/1494979200 - sold with 26 keys for Time Warp Tartan Spartan (50) = 24 keys

http://backpack.tf/profiles/76561198316071886#!/compare/1493942400/1494028800

http://backpack.tf/profiles/76561198030385019#!/compare/1493683200/1494288000 - sold for 24 keys

http://backpack.tf/profiles/76561198089111394#!/compare/1483660800/1492905600

http://backpack.tf/profiles/76561198176125115#!/compare/1492819200/1492905600 - sold in bulk for Blizzardy Storm Salty Dog (42) = bulk

Conclusion:

sales at 12, 24, 24, 24, 25

sellers at 21, 25, 25

taking 21-25 keys