We aren't a sign shop...this is an add-on to our print/copy business.
We have managed to get by with the aqueous prints by covering the outdoor stuff with a UV Laminate.
Holds up well....the imprint colors outlast the coroplast substrate.
Attached is a picture of a sign I printed up and only put the UV laminate on the top half.
The sign was out in the full sun and weather for 3 years. The UV laminate really did its job.