Item: https://backpack.tf/item/5262236499

Sale #1

https://backpack.tf/profiles/76561198131081286#!/compare/1600300800/1600387200

https://backpack.tf/profiles/76561198348959432#!/compare/1600128000/1600387200

Sold for Stormy Storm Master's Yellow Belt(active price suggestion at 105 Keys) + 1 Key

Sale #2

https://backpack.tf/profiles/76561198348959432#!/compare/1600560000/1600646400

https://backpack.tf/profiles/76561198123292125#!/compare/1600646400/1600732800

Sold for Snowblinded Winter Wrap Up(54.5 Keys) + 6 Keys = 60.5, rounding to 61 Keys

Sale #3

https://backpack.tf/profiles/76561198123292125#!/compare/1600992000/1601337600

https://backpack.tf/profiles/76561198160298174#!/compare/1600992000/1601078400

Sold for Haunted Ghosts Woolen Warmer(active price suggestion at 57.5, rounding to 58 Keys)

Sale #4

https://backpack.tf/profiles/76561198160298174#!/compare/1601078400/1601164800

https://backpack.tf/profiles/76561198960169972#!/compare/1601078400/1601164800

Untraceable

Sale #5

https://backpack.tf/profiles/76561198960169972#!/compare/1601510400/1601769600

https://backpack.tf/profiles/76561198292336517#!/compare/1601683200/1601769600

Sold this unusual + 41 Keys for Scorching Flames Nuke(99 Keys) [can use 55 + 41 = 96 keys there with this suggestion]

Sale #6

https://backpack.tf/profiles/76561198292336517#!/compare/1601769600/1601856000

https://backpack.tf/profiles/76561198220098345#!/compare/1601596800/1601769600

Sold this unusual + 39 Keys for Cloudy Moon Jumper's Jeepcap(suggestion at 90 Keys) [can use 55+39 = 94 keys there with this suggestion]

Sale #7

https://backpack.tf/profiles/76561198220098345#!/compare/1603670400/1603756800

https://backpack.tf/profiles/76561198878055432#!/compare/1603670400/1603756800

Sold for 49 Keys

Sale #8

https://backpack.tf/profiles/76561198878055432#!/compare/1604016000/1604275200

https://backpack.tf/profiles/76561198309178418#!/compare/1604188800/1604275200

Sold this unusual + Anti-Freeze Head Warmer(103 Keys) for Sunbeams Cat's Pajamas [can use 55 + 103 = 158 Keys, rounding to 160 Keys there with this suggestion]

Marketplace sales

Item: https://marketplace.tf/items/tf2/30413;5;u109

139.99/1.82 = 76.9 Keys(Oct 30), rounding to 77 Keys

Summary

Sales at

49 Keys

58 Keys

61 Keys

77 Keys

106 Keys

Conclusion

I'd suggest a price range from 49-61 Keys(avg. price 55 Keys) as the 77 and 106 Keys seems too high on average.