You can get Yorkville grille cloth (which they use on Traynor amps) through L&M.. some of it has a more vintage look than others. It's pretty cheap.. you buy linear yard x 1 yard wide.
I've bought a grill cloth from lopoline and the service was real quick. I ordered something from L&M once and discovered what the Long in the name means. You wait a long time for your stuff to finally come.