Needs a drop.

I know because I owned one.

Sold for 48 Keys*

http://backpack.tf/profiles/76561198047988051?time=1440486000

http://backpack.tf/profiles/76561198047988051?time=1441004400

*The keys were obtained by selling a Kill-a-Watt Executioner: http://www.tf2outpost.com/trade/26761908

Added 11 Keys for a Cauldron Bubbles Milkman(26 Keys with Overpay), a Dead Presidents Well-Rounded Rifleman(15 Keys with Overpay) and a Pro KS Scattergun Kit(15 Keys with Overpay)(45 Keys total)

http://backpack.tf/profiles/76561198011855197?time=1440140400

http://backpack.tf/profiles/76561198011855197?time=1440226800

Pro KS Scattergun Kit mini suggestion

All recent sales on the SCM(Keys = $2.49): http://steamcommunity.com/market/listings/440/Professional%20Killstreak%20Scattergun%20Kit

$40.85

$36.52

$40.01

$36.80

$36.79

$37.35

$49.01

$40.00

$52.15

$41.04

$40.65

$39.99

$44.64

$40.93

$45.90

$45.90

$40.24

$41.01

$41.86

$41.86

$48.84

$48.04

$49.58

$62.98

$62.98

The average comes out at $42.28(Roughly 17 Keys)

Two sales, 45-48 Keys should be fine.

Additional Proof/Counter-Proof/Constructive Criticism/Feedback is always appreciated.