Grimco sells Bantex two sided in both 13 oz and 18 oz versions. However there wouldn't have been an immense price difference on the banners. The 18 oz costs $740 for a 54"x50yd roll, while the 13 oz is $625 for the same size roll. Both do contain a blockout layer.
I checked with all the suppliers I use regularly and also Firesprint, and they only offer 18 oz vinyl for outdoor two sided banners. Perhaps that says something.
I did find that Showdown Displays offers a 13 oz smooth two sided banner for indoor use.
Doesn't help you now, but I find it's not worth bothering with trying to compete in the dirt cheap market anyway.
I checked with all the suppliers I use regularly and also Firesprint, and they only offer 18 oz vinyl for outdoor two sided banners. Perhaps that says something.
I did find that Showdown Displays offers a 13 oz smooth two sided banner for indoor use.
Doesn't help you now, but I find it's not worth bothering with trying to compete in the dirt cheap market anyway.