The company that installed ours has since stop trading, I know not why. The quality issue is key, our brackets fitted to the wall are similar to those that you get on a sailing boat, so will not rust, and are very sturdy, as are the metal eye holes in the plastic, once again same material as used on sailing boats. The plastic should be of a good thickness, and can I suggest that you avoid the use of colours like yellow or anything light, except white, as the sun will soon fade it. Finally make sure there are at least three vertical brackets on each side, and two/ three at the bottom, this will keep the plastic nice and taut when down. Oh yes and make sure the 'bands' that hold up the rolled up are good quality nylon (again sailing standard) with good quality locking clips.
Look and feel yourself, but also get a reference site that you can go out to see.
Good luck with the project, it really will be worth it.