How about one of these? http://www.ortliebusa.com/prod-90.htm
its a smaller, instead of, handle bar bag.

there is this one , but without the attachment to the handlebars..
http://www.ortliebusa.com/prod-235.htm


this is a bigger add on to snap onto their regular line of handlebar bags.
http://www.ortliebusa.com/prod-129.htm
http://www.ortliebusa.com/prod-151.htm