I recently purchased Charting Companion (a revision of the earlier PAF Companion). This program reads my genealogy software’s data file and can print a chart almost as large as I want. I’ve created charts as large as 3 ft by 9 ft, saved the chart as a pdf, and had it printed on a large format printer at a local copy/print shop.
Black and white charts of this size are not expensive to print. Color charts, on the other hand, are somewhat expensive.