That grille cloth looks like Tygon....
The Rexine Rolex is hard to find these days. The particular Rexine style you are looking for was widely used in book binding. This site has a fawn tolex but I dont think its the smooth style Rexine:
Fawn Vinyl NOS (New Old Stock) Rose Morris Vox Amp Covering
Word from my music colleagues is that JMI Amplification is the only current resource for Rexine and quantities are limited:
JMI Amplification
On a side note, this grille cloth looked close to the one in the image you posted:
All the best...