The OEM GTI ARB ist 23.6 mm in diameter and 3.5 mm thickness (hollow)
if I'm not wrong. I have written alle the ARB data in another thread.
A new one is about 100,-- . Or go for poly bushes instead.
But:
Are you sure the bushes being wornt out? The OEM ones are glued
onto the ARB, so just twisting, not rubbing on the bar, to make them
more reliable and last longer.
More trouble making: the sway bar links/rods !! They are about 30,-- .