replacement knob for ac/heater on Olds 88 (1999)

I'm looking for a replacement knob (or preferrably a better knob such as was on my 96 Chev Lumina) for the cheap plastic knob(s) on my ac/ heater controls of my Oldsmobile 88 (1999). The post looks pretty short (set back into the unit), but I would love to get some sturdier ones, such as the Chev Lumina (1996) style ones - rubbery surface and pretty heavy. Is there any good source for knobs that might do the trick? Thanks for any help in this.