better question, what's YOUR pricing on install trucks?
Box truck I'd assume what, 8hours labor uninstalling/prepping and install 4hours labor? Multiply by your hourly rate for labor, add x% for profit, and x% for taxes, and x% for good measure (warranty, shop supplies, etc.).
Ultimately up to you to determine the scale of the work... and what you're worth.
edited: I'd say $400 a truck. $200 removal, $200 prep/apply