from cheat sheet:

Steam Community Market Sales

For each SCM sale, please provide proof (screenshot) that the hat of that particular effect sold for the said price

To determine a trade value, you should take in consideration BOTH what a buyer paid and what the seller sold (i.e. you will get a range from a single sale. low end = what the seller received; high end = what the buyer paid)

Buyer value: If the hat is >1 buds in value, take the sale value divided by the value of buds AT THE TIME. If the hat is <1 buds in value, take the sale value divided by the value of keys AT THE TIME.

Seller value: First factor in steam tax. Divide the sale value by 1.15. Then divide the result by the value of buds or keys at the time of the sale as appropriate.

Treat SCM sales as you would other sales - compare the sale value to other sales and b/os to determine if it is an outlier)

Which is what he has done

5 days isn't a real quicksell. especially at 30%+ off current price

Well, there are only 2 other usable sales that I can see on all in existence. One was your purchase which seems to be for a blizz pusher. And then there is the sale before that which seems to be for a TW dco, which is heavily outdated. Buyer hasn't been able to sell for 7 in more than 2 months even though it's listed at 8+. That sale is pretty old anyways. More than 2 months old.

Going with the two recent pure sales.