I'm on my iPod at the moment so I won't be able to provide links (my iPod is kinda touchy
But anyway! I highly recommend, if you live near by one or all of these places, checking out Walmart or JoAnn's pattern selection. Lately pattern companies have been catering to the cosplay community.
Or you could check out the pattern company wedsites (Simplicity, McCalls, Butterick, etc) for anything the stores might not be carrying.
There are a number of coat patterns that could be adjusted into a Vash coat.