I have made good banners with nothing more than old bedsheets
or leftovers the local cloth store had on sale. I have
found cloth used for the inside lining of business suits to be very
light and thin and make great flags.
Spray-paint will stick to most anything and last for
years. The paint will bleed through, which is great for
flags because you then get the reverse image on the back side with
no additional work. But the bleeding will also paint
whatever you have the cloth laid/tacked on to, so be
careful. Also test the paint and cloth by painting on a
dab, letting it dry, and then twisting it up to be sure it will
stick properly. It sucks to put a lot of work into a banner
and discover the paint comes off when you fold it!
The cloth stores here also sell the rings you can attach to
the corners so you can hang your banner properly. You can
also twist and knot the corners and just tie a rope to it that
way.
If you have a specific image in mind, make an overhead slide,
hang the cloth on a wall, and use an overhead projecter to
project the image onto the cloth, and trace the
image. I got a cheap overhead projecter here at an
office supply store for about $150.00 USD
My "keeper" is one made of two "queen size" bedsheets sewn
together and spray-painted by a graffitti artist I hired. (I
had to pay him cash and he wouldn't to tell me his
real name, but he did a fantastic job at a fraction of the cost of
what a commercial banner would cost). It measures a little
more than 5m x 5m. We hold it over fans heads when they
introduce the players, but only for the 'big' games.
So if yall have an artist or two, why not make it a
party? Bring cloth, beer, tunes, an overhead projector,
markers, and paint to a location where they don't mind a little
spray-paint, and let your artists have at it. They might
not all be professional looking, but they will be
affordable; and I have found our players appreciate the effort
more than the results, if you spell their names
correctly.