https://imgur.com/a/qp4xAoB - seller at 26, buyer at 15

https://bot.tf/stats/listings/4ZP5J02D - around a week at 26 (Charlotte is Julia (marketplace.tf)'s bot)

https://marketplace.tf/items/tf2/31041;5;u10 - mp buyers up to $28 = 14 keys

Because of these buyers, 14 is low.

Sale 1 likely sold for 24

https://bot.tf/stats/listings/Y9Q0DEE0 - B/O was 24, like

Another sale:

https://backpack.tf/profiles/76561198095022965#!/compare/1590278400/1590451200

https://backpack.tf/profiles/76561198203978028#!/compare/1590278400/1590451200

https://bot.tf/stats/listings/4ZPEEO8D - B/O of 40

Sold for a Peace Wraith (22, see mini) + Strange Specialized Killstreak AWPer Hand (~10) + 3 keys

22 + 10 + 3 = 35

X = 35

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Wraith Mini:

https://backpack.tf/profiles/76561198311498888#!/compare/1589932800/1590019200

https://backpack.tf/profiles/76561198203978028#!/compare/1589846400/1590019200

https://stntrading.eu/item/tf2/Unusual+Circling+Peace+Sign+Wraith+Wrap - sells for 22 keys 12 ref?

Looks like added 24.66 ref for 22 pure, this or the stn price, would round to 22

X = 22

Only usable sale so free suggestion for you on that

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If the seller at 26 remains unsold (which I have a feeling will be the case), this is probably best as 23 flat. If it sells, you could probably do 23 - 26, or maybe 23 - 35, but 35 is probably high if it remains unsold for much longer.