After doing purple and fetti I think that this price also needs an update. Here's why:

http://www.tf2outpost.com/trade/10005709

avery again (also on purple) has a b/o of 22, and a claimed c/o of 19 in only 6 days

the visible offers are 14-15 and an "added I pay b/o". that guy hid his own post and at least at the moment has nothing near b/o in pure

His hat is now in "goat"'s backpack but he offered on neither of avery's trades

avery bought for http://www.tf2outpost.com/trade/9912584 17 keys

http://www.tf2outpost.com/trade/10058032

bad boy avery, having 2 trades for 1 hat,

only offer is a bubbling ketche (updated VERY recently here to 12-14)

http://www.tf2outpost.com/trade/10066739

values his hat at 19-20 keys, wants ANY engi hat with planets

http://www.tf2outpost.com/trade/8996127 he bought for 10 keys, wrapped shades, clean teddy, clean satchel, and the mtm taunt. (around 17 keys)

as 2 were bought for 17, the top end is that, and the low end 15 as that's the highest offer. (I know that means nothing, but as the current owners bought for b/o's of 17 that is the top end, and it kinda needs a range now doesn't it.