I am guessing this might be a landlord request of the shop owner to conform with other existing shops? Other than “if” it has to be rolled up and down, as I don’t see the point in it and looks pretty poor for what you could offer him. if it doesn’t need to be rolled, a simple flat plate of steel drilled and welded to the ends of a tube of steel and painted with a Hammerite type finish and secured with some thunder-bolts from Screw-fix would do the job. If you don’t do that in-house, most small steel-work fabricators will knock this out cheap. You then just have the banner to make yourself and your jobs are done. Alternative routes, aluminium or galvanised steel, powder-coating etc are better but long-winded and more expensive.
As you well know, there are lots of options you could offer with a much better visual appearance. Even just swapping the round poles to square tubing and riveting or tech screwing a sheet of composite to the tubes would be much better looking and far longer life.