Here's an old sale but it also sold for 2 Flies Racks on Apr 10th

Mini for Private

http://www.tf2outpost.com/trade/25604102 Sold for 2 Flies Racks

X = 33*0.9 + 33*0.9

X = 59

Rack 1 http://backpack.tf/item/3591541106

Rack 2 http://backpack.tf/item/919937030

Private http://backpack.tf/item/2047291046

Right, I have no idea why did you do a mini-suggestion on the Stove Pipe if you just valued it at 68 Keys at the end.

Anyways, valuing the Stovepipe at 80 Keys is way too high. Seems like the guy likes overpaying as well: http://www.tf2outpost.com/trade/25807610

A mini on the Stovepipe:

Sold for a GE Samur ~68 Keys

http://backpack.tf/profiles/76561198067163843?time=1435300016

http://backpack.tf/profiles/76561198067163843?time=1435388400

GE Samur was then sold for 68 Keys http://www.tf2outpost.com/trade/26018467

Currently has B/O of 80 Keys: http://www.tf2outpost.com/trade/26630844 & http://www.tf2outpost.com/trade/26463665

Also, as Face has said below, Sober needs a mini as well.

Sold for Blizz Scotch Bonnet (11 Keys) + Sweets (~1 Key) ~12 Keys

http://backpack.tf/profiles/76561198167587658?time=1436140870

http://backpack.tf/profiles/76561198167587658?time=1436252400

Therefore, the total of your sale should be 68+12+2=82*0.9= ~74 Keys

Of course, there are also other sales as you've said below.

Sold for Bonzo Danger (131 Keys) w/ Frostbite Whirly (72 Keys) ~59 Keys

http://backpack.tf/profiles/76561198059523054?time=1434338927

http://backpack.tf/profiles/76561198059523054?time=1434870000

Should be offered on the Danger, therefore no overpay on Danger: http://www.tf2outpost.com/trade/26137149

Bonzo Danger: http://backpack.tf/vote/id/55a75261ba8d88511a8b48e9 (120-142 Keys)

The other sale is quite complex, avoiding it should be best.

Looks like another was sold for a C9 Rebel (22 Keys) + Steaming Glove (14 Keys) + Pro. KS Aussie Blut (~15 Keys) + 3 Keys ~53 Keys

http://backpack.tf/profiles/76561198119556784?time=1433660400

http://backpack.tf/profiles/76561198119556784?time=1433798516

http://www.tf2outpost.com/item/440,3835160238,388,5

Mini on the C9 Rouser:

Sold for G.Fetti Thirst Blood ~22 Keys

http://backpack.tf/profiles/76561198090822133?time=1435561200

http://backpack.tf/profiles/76561198090822133?time=1435647600

Mini on the G. Fetti Thirst Blood:

Sold for Stormy Storm Human Cannonball ~22 Keys

http://backpack.tf/profiles/76561198137889680?time=1431154800

http://backpack.tf/profiles/76561198137889680?time=1431759600

Another was sold for a Duped Burning Dapper's ~61 Keys (Using Clean Price*0.81)

http://backpack.tf/profiles/76561198110986871?time=1433660400

http://backpack.tf/profiles/76561198110986871?time=1433746800

So, sales are 53, 59, ~61 & 74 Keys, I would do 53-61 Keys.

Your sale should be an outlier considering that 68 Keys on the Duped Knifestorm Scotsman's Stove Pipe might be still high even at 68 Keys.