We stock bunting tape in all colours of the rainbow! It's a cotton twill which is much better than using bias binding which stretches.
The bunting tape is available by the metre & is available in 30mm, but also available in 20mm, 14mm & 11mm widths in white & cream, so simply fold it in half, insert your flags and stitch!!! It makes great bag handles too.
50m discounted rolls are available here.