Tom,
questions to ask yourself:
How long will it be up?
How far away from viewing?
What is lighting like?
A banner of this size is typically seen at a distance. Which means the distance can make even a poor
print look OK. If it will be seen close up, say 2-3 feet, then a good photobase product would be a
reasonable media. I would stick with satin.
If it will be seen from a short distance then many good poly products offer great quality at a much
lower price point.
Where do you live? I may have a referral for you.