Gear knob gaiter plastic

I needed to remove the knob gaiter to adjust the gear linkages, pin through the hole and all that....

I managed to remove the chrome collar, but the plastic round thinghy that holds the gater in place would not come off. I pulled and pulled untill it snapped.

Q. Where do I find a replacemet for that? Do i need to buy all the gaiter assembly (knob, collar, chrome ring etc) ? I can't seem to find anything on eBay.