Taking last 2 months.

Sale 1: Sold for 28 keys

https://backpack.tf/profiles/76561198823739367#!/compare/1588896000/1588982400

https://backpack.tf/profiles/76561198384098743#!/compare/1588896000/1589068800

Sale 2: Sold for Stormy Storm Coldsnap Cap (25 keys) + 6 keys

https://backpack.tf/profiles/76561198122976167#!/compare/1589500800/1589673600

https://backpack.tf/profiles/76561198202053684#!/compare/1589414400/1589673600

25 + 6 = 31 keys

Sale 3: Unknown

https://backpack.tf/profiles/76561198122976167#!/compare/1589414400/1589500800

https://backpack.tf/profiles/76561198170143095#!/compare/1589414400/1589500800

Sale 4: Unknown, though I think keys were involved

https://backpack.tf/profiles/76561198263599385#!/compare/1589414400/1589500800

https://backpack.tf/profiles/76561198170143095#!/compare/1589414400/1589500800

Sale 5: Sold for 14 keys

https://backpack.tf/profiles/76561198263599385#!/compare/1589241600/1589328000

https://backpack.tf/profiles/76561198311498888#!/compare/1589241600/1589328000

Sale 6: Sold for 25 keys

https://backpack.tf/profiles/76561198156255538#!/compare/1587859200/1588032000

https://backpack.tf/profiles/76561199040264892#!/compare/1587686400/1588032000

Sale 7: Sold for atleast 8 keys

https://backpack.tf/profiles/76561198850274253#!/compare/1587600000/1587686400

https://backpack.tf/profiles/76561198156255538#!/compare/1587686400/1587600000

Sale 8: Unknown

https://backpack.tf/profiles/76561198249078668#!/compare/1587427200/1587513600

https://backpack.tf/profiles/76561198850274253#!/compare/1587340800/1587427200

Sale 9: Sold for 25 keys + 34 refined

https://backpack.tf/profiles/76561198847672167#!/compare/1586995200/1587081600

https://backpack.tf/profiles/76561198249078668#!/compare/1586995200/1587081600

25 + 0.63 = 25.63 rounding to 26 keys

Classifieds:

https://gyazo.com/809f700b6769daecacced1dd5984cc4c

Sales are at 14, 25, 26, 28, and 31. Buyers are at 15+. Excluding 14. Taking a range of 25-31 keys here.