Same proof as this suggestion (https://backpack.tf/suggestion/6112643a000175634c61372b#comment-61126b7bb19f101b3803fb50), except taking into account the fact that in the second offer:

-The tank top's price is realistically 8 keys. Tank top has a bot selling for 8 keys buying at 7.7 keys, human selling for 9, so it's realistically locked at 8 keys.

-The tailor has a seller at 12 keys rn, although the one used in this trade was just 1 for 1'd with the Circling Peace Sign Hephaistos' Handcraft (bots buying at 10k pure). https://backpack.tf/profiles/76561198170427507#!/compare/1628380800/1628467200 realistically making it between 10-12 keys.

The relevant sales in that suggestion were:

1.)Sale for 13 keys, 1 key in skins, and holy grail deep fried desire (price 3 keys with bots currently buying and selling at around 4.4 https://imgur.com/a/lbQWQV5), so overall around 18 keys. https://backpack.tf/profiles/76561198013011182#!/compare/1627862400/1628035200

2.)Sold for Cloud 9 Toy Tailor (15 keys) and Orbiting Planets Tank Top (9 keys), so 24 keys in mixed by official pricing, however based on comments on the other thread it's realistically 10-12 keys and 8 keys, making this offer 18-20 keys in mixed. https://backpack.tf/profiles/76561199184202540#!/compare/1628035200/1628121600

3.)Purchase for 15 keys pure https://backpack.tf/profiles/76561198056475023#!/compare/1628380800/1628467200

All other variants of the hat either have weird bulk sales, are untraceable, or haven't been traded yet.

Overall, this leaves us with a sale of 15 keys pure, 18 keys in mixed that's essentially pure, and a sale for 18-20 keys in mixed items.

Based on these sales, 18 keys seems like a solid price point for this item as it essentially had 2 sales for 18 keys pure (if sold to bots) and the 15 key buy seems to be a quickbuy. 18 keys also seems more reasonable considering the current lowest seller wants 20 keys (https://imgur.com/a/IPvbRul).