https://backpack.tf/profiles/76561198150783829#!/compare/1493596800/1493683200 - Aces Buddy + 7, ~18

http://www.tf2outpost.com/trade/28881057 - Had been asking 19 for 2 weeks

^Only a week prior to the Bitey sale.

The Bitey sale is somewhat bulky and skews the value of the Naggen - I wouldn't use a sale like that as sole proof for a suggestion, only if there were other sales to support its value (in relation, the whole hat must be 50% of the trade thing is really meant to decisively exclude sales where it is less than 50%, not as a clearance to use anything where it is more than 50%). The Big Country sale looks more like it would support a refresh tbh - multiple sellers there asking for 40.

I think 18 flat would be best here.