Your local Toyota garage can usually have them ordered in for you in a few days, I think mine cost about £5 or something similar (maybe less, it was so long ago).
It seems that the Jap spec cars have the worst job in removing the screws due to the amount of frickin locktite that those crazy Japanese engineers use!! Yes use the correct screwdriver size, not one that *seems* to fit - you *WILL* round the heads off and that is not nice! Some people find heating the screws up with one of those micro windproof pocket lighter/blow torch thingies helps (not so hot you are burning/bubbling paint though ).
Alternatives that have been suggested that I never tried (but some claim work) - wd40 the rubbers, sports tape (or similar) on the rubbers (soft cushioned stuff with sticky one side you can buy at sports shops), turning the radio up ...