actually... they don't.
(have the patches, that is.)
if you look at the new gof site... www.gobletoffire.co m
... it shows the gang in their scarves (which makes me soooooo happy!) and there is no patch.
i knitted a poa/gof style scarf in gryffindor colors for the 6th book release... (i didn't wear robes because i live in az, plus the knitting took up a good chunk of my time!) i modified the atypically.knit pattern into 1x1 ribbing. (plus i knit on size 15s!!! i am a tight knitter)
many people wondered if i bought the scarf... then i told them the answer by pulling out my knitting! (i was making a go-go garter scarf from snb for a friend)
i even had a girl try to commission me to make her a scarf... but i couldn't. (i barely finished my own... i was weaving in my numerous ends and putting on fringe that day at work!)
the best part about the scarf is that it doubles as a late season football scarf for arizona state university (where i go...)!!!!! so a colorblock scarf would be a bit more harry potterish, but at the same time... total sun devil pride...