If you bring the image on a flash card into one of the printing houses downtown they'll print whatever size you want. Most of them have all the sizes and rough prices displayed. I've seen decent quality prints on foamcore (1/4" foam board with a high gloss paper finish). But thats more of a custom job. Getting a print on just normal presentation paper should be pretty easy. It'll probably only take a couple of hours.
Our office uses these guys:
http://www.carboncopydigital.com/
This place is also popular:
http://www.westcanadian.com/about_us/news.html
I think even Kinkos and Staples might be able to do it. I think I know what you are up to, but keep in mind that the bigger you make the image the more you lose quality. So try to have the highest resolution image possible.