How accurate are you looking for? Movie accurate?
I may have some pics - I'll see if I can fish them out and pop them up on Flickr. (It may take a couple of days as I'm a bit busy getting voldemort ready for this weekend, but I'll post them up as soon as I can.)
In the mean time, check out a site called "Oclumencia" as they have a brilliant library of pics. (It's a Brazilian site and so until you get familiat with the layout you may want to run it through Google's translator from Portuguese to English. however, if you do that you won't be able to view the high res images, but once you're familiar, just make a not of the path to the image, and do it direct rather than using Google ) (I hope that makes sense)
Which version are you thinking of (as they changed a few times), and was there a particular character?
I dont often recommend stuff on ebay, but I seem to recall seing what was actually a pretty good recreation on there a little while back. I've just had a quick look and can't seem to see it there at the moment but I'm sure it will pop up again at some point as it was from a company as opposed to a "one off" if I remember rightly.
Also, I'd check out the behind the scenes programs as there's a fab one just on the various costumes, and I remember they mentioned the quidditch robes specifically in one of them.