Go to the signage printing industry
Sometimes technology intended for one industry is perfect for another industry and this is a case in point. Find a small business near you that specialises in printing large vinyl signs for the advertising industry. Their rates are usually significantly cheaper than photographic printing and the results are every bit as good. And they have some advantages. The printed surface is waterproof, abrasion resistant and fade resistant in direct sunlight for five years.
Normally printing is done using a printer such as the Roland Versacam 540 on self adhesive vinyl rolls, from a company like Oracom, with a peel off backing layer.
Once printed, the backing layer is peeled off and the print is adhered onto a suitable substrate. I mount my panoramas on white 0.9 mm ABS plastic. This is commonly used in the advertising industry for mounting large display adverts. It is easily cut and mounted. This avoids the formidable costs of framing and mounting.
The scary part is trying to adhere a self adhesive 2m long panorama without wrinkles or bubbles. In fact it is amazingly easy once you know the tricks of the trade. Your signage company will be happy to show you. In outline, you peel away the backing and spray on a very dilute water/detergent solution (very dilute!). The adhesive is no longer sticky and you can easily position the print on your mount. Now you squeegee the excess water out until you have a wrinkle and bubble free result. The print is now firmly bonded to the substrate. Oracom make an excellent fabric squeegee and this is what makes all the difference, don't use anything else.
I printed and mounted many large panoramas in this way (to the dismay of my wife who is reluctantly conceding all the wall space) and can attest to the fact that it is inexpensive, quick and simple to do.