Totally not overpriced at all.

https://backpack.tf/item/6360055649

Sale 1) ?

https://backpack.tf/profiles/76561198065959797#!/compare/1538438400/1538784000

https://backpack.tf/profiles/76561198051914219#!/compare/1538524800/1538611200

Sale 2) ?

https://backpack.tf/profiles/76561198123631904#!/compare/1540944000/1541030400

https://backpack.tf/profiles/76561198072565193#!/compare/1540857600/1541030400

Sale 3) ?

https://backpack.tf/profiles/76561198072565193#!/compare/1541030400/1541116800

https://backpack.tf/profiles/76561198053717045#!/compare/1541030400/1541116800

https://backpack.tf/item/6274490314

Sale 4) Sold + 7 Keys for a Duped Burning Flames Troublemaker's Tosslecap (110 Keys)

https://backpack.tf/profiles/76561198072565193#!/compare/1541203200/1541548800

https://backpack.tf/profiles/76561198061779536#!/compare/1541289600/1541376000

110 - 7 = 103 Keys

Tosslecap Mini

https://backpack.tf/profiles/76561198232041512#!/compare/1545436800/1545523200 - Sold for 110 Keys

https://backpack.tf/suggestion/5c2a6d4f44325a593c18e5cc - The rest of the non-usable sales are here.

https://backpack.tf/item/5991105927

Sale 5) Sold for 97 Keys + 6 Refined

https://backpack.tf/profiles/76561198125791160#!/compare/1541376000/1541462400

Rounds to 97 Keys

https://marketplace.tf/items/30862;5;u13 - Sales at $320 (almost outdated), $442 (high), $280, $150 (low), $219.9, $210, and $250

https://marketplace.tf/items/5021;6/Mann%20Co.%20Supply%20Crate%20Key

Keys were $1.78, $1.83, $1.78, and $1.74 when the valid sales happened, respectively. That makes the sales 157.3, 120.2, 118, and 143.7 Keys.