If you only have to ship banners on occasion, you could always use Signs365 and have them drop ship to your customers. We do this on any banner jobs that need to be shipped. They package the banners very well and we've never had a customer make a claim over damaged goods. They use your mailing address as the shipper's address, so no worries there, either.
That being said, the way they do it is they roll banners up with the printed sides facing inward, wrap the bundle together with cling wrap, put them in a shipping tube with end caps, and then place that inside a rectangular box. It's probably not the most affordable shipping option, but it doesn't get much better than that as far as reliability, which is what I'd personally be more concerned about over cost.