Material for wavey tifo flags?

Could someone tell me what type of material I should be looking for for a wavey big flag, or even better somewhere in Dublin that would have the stuff and I could get a custom flag done. Also, about what size material would be best for a 5.5 metre telescopic flag pole.
Cheers

Any fabric place will do it. Get as light as material as possible. Best/Cheapest is lining material. Its about €3.80 a metre (1.5m wide) but if you buy enough of it you get it substantially cheaper. You will need to sow it