I agree that the moulded plastic heel tips commonly found on so many (women's) shoes are unduly noisy and don't wear too well.   (And I've never found a source of them as replacements either, even by searching trade sources.   Too many variations in size and peg-location, perhaps?   What do cobblers use as replacements, I wonder?  Or are shoes with such worn-out heels usually abandoned?)
 
	I'm probably not suggesting anything new to you, but I have found that one straightforward technique for tip replacement on block heels is to fit a piece of softwood into the hollow heel.   It can be quite easily shaped to be a rough push fit and flush with the underside and will not usually require any adhesive to secure it.   A suitable piece of rubber (possibly salvaged from some otherwise worn-out men's heels, or cut from a sheet of heel material) can then be stuck and/or nailed to the wood and further shaped to the right profile if necessary.   Nailing gives extra security, particularly on any heel less than 25mm or so across; brass gimp pins (about 12mm) are ideal as they will wear with the rubber.