Counter Suggesting due to the lack of evidence on the other one :/ Thanks for Kazooie on the correct range

Sale 1: Sold on SCM For roughly $24 or Rounded up to 10 Keys Was on the SCM For about a month

http://steamcommunity.com/market/listings/440/Unusual%20Ol%27%20Geezer

https://backpack.tf/profiles/76561198254667858#!/compare/1500336000/1500422400

https://backpack.tf/item/4344411602

Sale 2: Sold for about $24 Again on SCM Taking 10 keys, Took 2 days

https://backpack.tf/profiles/76561198177042893#!/compare/1500768000/1500854400

https://backpack.tf/item/4344411602

Sale 3: Sold for a Pro KS Pan Taking 10 keys (Had it for 2 months)

https://backpack.tf/profiles/76561198085628805#!/compare/1494374400/1494460800

https://backpack.tf/profiles/76561198353843277#!/compare/1494374400/1494460800

Sale 4: Sold for Strange Spec KS Festive RL (10 Keys) + 5 Keys, 15 (1 Day)

Probably sold his australium or the machina to get keys

https://backpack.tf/profiles/76561198085628805#!/compare/1494547200/1494633600

https://backpack.tf/profiles/76561198041902665#!/compare/1494547200/1494633600

Sale 5: Sold for 10 keys I guess due to matching key history (2 Days)

https://backpack.tf/profiles/76561198219304340#!/compare/1494720000/1494806400

https://backpack.tf/profiles/76561198041902665#!/compare/1494720000/1494806400

Sale 6: QS it for 8 Keys?

https://backpack.tf/profiles/76561198093540044#!/compare/1495065600/1495756800

Sale 7: Re-QS For 6 keys and 2 keys in items?

https://backpack.tf/profiles/76561198093540044#!/compare/1496188800/1496707200

Sale 8: QS For 8.5 Keys I guess? Histories match

https://backpack.tf/profiles/76561198294005768#!/compare/1496620800/1496707200

https://backpack.tf/item/2583462009

Sale 9: QS for a ton of junk that adds up to, 8.5 Keys i guess?

https://backpack.tf/profiles/76561198253510225#!/compare/1496793600/1496880000

https://backpack.tf/profiles/76561198174121615#!/compare/1496793600/1496880000

Sale 10: Wot

https://backpack.tf/profiles/76561198174121615#!/compare/1496966400/1497052800

https://backpack.tf/profiles/76561198236708484#!/compare/1497225600/1497312000

Sale 11: Unusual History don't match?

https://backpack.tf/profiles/76561198236708484#!/compare/1498003200/1498089600

https://backpack.tf/profiles/76561198095581099#!/compare/1497744000/1498089600

Sale 12: Histories Don't match :/

https://backpack.tf/profiles/76561198052615128#!/compare/1498435200/1498608000

Sale 13: Added a key for a P Fetti Back Biter's Billycock (16 Keys) Adds to 15 (Had for a day)

https://backpack.tf/profiles/76561198299721181#!/compare/1498435200/1498521600

Sale 14: 1:1 With a Circling Peace Sign Sober Stuntman (12 Keys) Took a day or less

Sale 15: Sold for a Circling TF Logo Electric Escorter (11.5) + Rancho Relax (17 Refined) Rounding to 12 (8 Days)

https://backpack.tf/profiles/76561198084205929#!/compare/1499126400/1499212800

https://backpack.tf/profiles/76561198296323767#!/compare/1499212800/1499299200

Escorter Mini:

https://backpack.tf/suggestion/59833151cf6c753125214c55

Sale 16: Was QS to Scrap.tf then bought instantly for 10 keys

https://backpack.tf/profiles/76561198081847001#!/compare/1499472000/1499817600

Sale 17: QS For 5 Keys .-. Whyyyy

https://backpack.tf/profiles/76561198081847001#!/compare/1500249600/1500336000

Sale 18: Bulk probably

https://backpack.tf/profiles/76561198375401567#!/compare/1499385600/1499472000

Sale 19: QS the unusual to scrap.tf to buy this for about 10 Keys? (7 Days)

https://backpack.tf/profiles/76561198093515852#!/compare/1499472000/1499558400

https://backpack.tf/profiles/76561198337734785#!/compare/1499472000/1499558400

Sale 20: Something yet again :/

https://backpack.tf/profiles/76561198272277280#!/compare/1500249600/1500336000

https://backpack.tf/profiles/76561198314349856#!/compare/1500249600/1500336000

Sale 21: 1:1 With a Duped Bubbling Old Guadalajara (13) (3 Days)

https://backpack.tf/profiles/76561198314349856#!/compare/1500422400/1500508800

https://backpack.tf/profiles/76561198344921773#!/compare/1500422400/1500508800

Old Guadalajara Mini: Was sold along 1 key and some refined for a Tesla Coil Cranial Carcharodon (14.5) Gonna round down due to it being duped

https://backpack.tf/profiles/76561198026991610#!/compare/1500508800/1500595200

Sale 22: 1:1 With a G.Fetti Sober Stuntman (9) Had it for 18 days

https://backpack.tf/profiles/76561198344921773#!/compare/1500508800/1500595200

https://backpack.tf/profiles/76561198063071690#!/compare/1500595200/1500768000

Stuntman Mini: Unsold at 9.53 for 2 months, Gonna round down

Unsold:

13 Keys For 8 days

Well this took some time though total sales:

5

6

8

8.5 (x2)

9

10 (x6)

12 (x2)

13

15 (x2)

Seems to sell the most at 10 and 12 so taking that range