Finding a big scanner

My scanner will scan art up to about 9"x12", but as many of you folks know, standard comic art is bigger than that -- 10"x15" for non-bleed, or thereabouts, more for bleed art.

Scanning my black-and-white line art in multiple passes and stitching it together is doable, but a pain; for one thing, there's always a little distortion that has to be clipped from the topmost layer -- some high-zoom nudging -- and sometimes some touching up -- before merging layers is safe. At least, that's what happens with my scanner, as like most office-oriented scanners it's got a lip around the glass for lining up the edge of the paper, but anything that goes off the edge gets distorted at that edge.

Color/grayscale art of that size? I don't dare. The tones are just too hard to match. (Or are they?)

Anybody got any ideas on where to find a big scanner -- preferably something that won't cost more than an arm and a leg?