http://www.tf2outpost.com/trade/25698844 - 5.33 ref (young, buyer);

Here's more sales:

http://www.tf2outpost.com/trade/25655892 - 4 days old (6 ref);

http://www.tf2outpost.com/trade/25684063 - 1 day old (7 ref, quicksell);

Your current 5.33 ref link is 18+ hours unbumped in 1 day, that's sorta horrible.

I'd advice 6 ref flat, or 6-7 range, if you can't find a good and valid 5.33 seller, unbumped sellers aren't considered good proof most of the time.

---*Edit*---

Every other outpost sale is above 5.33 ref or offers, only one 5.33 seller and horribly bumped.

Downvoted from my part, as 5.33 shouldn't be in range.