I've been getting large format prints for work and found the best deals are:
$6.13 per square foot for a print with solvent based inks on 3 year exterior weather resistant adhesive vinyl.
or $11 per sqaure foot for a 3M Scotchprint with UV laminate, which IMO is a little overkill unless you're planning on constantly running your cab outdoors in blizzard conditions.
These prices are based on 8' x 4' prints I've been using for construction site signs, but I could more than likely get the same prices for my own stuff.
How does this compare to what everyone else has been paying?