im not accusing you of anything but you just gave me an idea :

step 1 use an alt to buy many copies of a hat

step 2 buy one hat for more than backpack.tf price

step 3 make a price suggestion

step 4 sell all your hats

step 5 profit

I really sorry if you see this as an accusation, I just wanted to point it out I swear

EDIT the fact that there's a 3 key buyer leads me to think that this price suggestion is valid