Ok, here is my report from the front. I went up to Kinko's today and printed out 3 backgrounds. They didn't have time to do it for me, so they directed me to a computer with Photoshop and a nice color laser printer.
They charged me $.20/min for the computer time and $1.08 per copy on card stock. This ended up costing me about $1.50 per background I printed. This is mostly because of the rendering time that Photoshop needed to generate the print job.
I would recommend that you get the backgrounds properly sized for the cel before you get there. I messed up a few times and wasted about $5 on botched printouts. I printed out the backgrounds with 14" X 11" print area. This was good because I think the paper they gave me was 17" X 14". I'm not sure because I trimmed down the printouts after I got ones I liked.
One other thing to be aware of is Photoshop will decide the best way to display the image. This is not always good. For example, on one of the backgrounds I printed, it chopped off the top. This made it hard because I lost the registration holes...
Right now, I only have a single cel scanned in with a copied background. If you'd like to see how it turned out, look here:
http://cyphr99.rubberslug.com/gallery/inv_info.asp?ItemID=46315
It was an almost perfect match of the shot. Thanks to lonelymountain for the donation!