Or check out Vintage Joe's he has some nice handles for a reasonable price. Golden Nib has new handles for around $20 so I wouldn't pay more than that for a vintage given the extra work that will be involved in cutting out the old knot.
As well as antique shops and the like, I like the look/prices of a few of these
http://www.whippeddog.com/As-Received-Brushes/
Larry's a great guy to deal with and the knots he carries are top notch to boot I'd much rather deal with him than hassle with ebay and more than likely overpay
(disclaimer: I have no affiliation to whipped dog razors other than being a very satisfied customer )
EDIT: great... i found one i couldn't resist...
thanks a lot