feather flags
 

anyone ever bought one of those 12ft advertising flags you put out in front of you shop?

I see some that don't really stand out as far as the colors and then I see some that the colors are more vivid.

how about a site to get a good deal on one?

I would bet there are several local places that do point of sale or large format printing do it. They will print whatever colors or text you want.

ours lasted about a year, then faded and shredded in the wind.

I have a vinyl cutter and can make them, but frankly I go to Vistaprint.com for stuff like that. Not much more than my cost of materials.

looked at vista, $200. need to find out if that is double sided.

You might try your local skydiving DZ, skydiving gear stores (Para Gear, Square 1, etc.), or even canopy manufacturers (Performance Designs, Icarus, etc.).

I am pretty sure they first appeared within the skydiving community. That's where I first saw them. We called them "wind blades" or "air blades" IIRC. DZs would/do use them for hi-viz windsocks, and to identify/border landing areas.
Then someone finally realized they would make good ad-banners and the rest was history. The ones from skydiving-related sources should be better quality as well, as most use modern rip-stop parachute fabric (zero-p, UV-resistant, etc.).