I'm not sure what you consider expensive, but have you looked at www.cafepress.com?
They are essentially a storefront that charges a base rate, then you set the markup if desired. Everything is made to order. If a customer wants a bumper sticker, they make a bumper sticker and send it.
here's their pricing structure:
http://www.cafepress.com/cp/info/help/pricing_policy.aspx
-jay

Unfortunately they are expensive, I managed to order a couple in bulk when I did, but I no longer have anymore.

Jason M. Connolly
Instructor
Martial Arts Center
433 Amherst St.
Nashua, NH 03063
603-598-4200
jconnolly@kungfutaichi.com
www.kungfutaichi.com