Barnsby do one with elastic inserts, but if you want all elastic you might have to get it made to measure. There is a forum member who does this (k9h I think!
It's not fully elasticated but it was the only one I could find when I was looking. Unfortunately you have to buy the whole bridle as they don't sell the nose band separately.
The ones with nice thick elastic as opposed to elastic inserts?
Bloody nightmare to find! Jefferies used to manufacture them for the polo market but only sold a handful each year, so stopped producing them.
Bossanova found one for my muppet in a closing down sale at a saddlery and it was a very handy piece of kit, so I would suggest local saddleries and places with second-hand sections.
I asked around dozens and dozens of saddleries in my quest to find a full-size one, and general consensus was to get one made as there are so few around