I don't wanna say which auction or item (you know, the rules) it is but it goes like this.

Tile: starting at buy order 15 keys,
in the backpack classifieds there is 1 guy buying it for 15 keys and 10 are buying for 12 keys,
The seller and and the 15 key buyer are friends on steam.

Don't know if someone is trying to manipulate the system or am I overthinking because I lack sleep.