You can probably find a local sign maker business who can make one to order, there is a Franchise sign business chain that specializes in digital printed banners and signs.

Give Aura Print a call, 01484 429300, or take a look at http://www.auraprint.co.uk/ - their bespoke banners are designed by a person and the prices are good too.

Good thing you asked, check out http://www.printandmail4u.com they really have an awesome designs for your banners and 100% customizable and personalized ;)

Amazon. They have anything you can think of. Even glow in the dark toilet paper