Try your local bike shops. Also it helps to use some good quality hex wrenches when undoing such small screws. Some cheaper ones are made of soft metal and sloppy tolerances and easily strip the screw heads. I usually end up grinding down my 2.5mm allen wrenches a couple of mm after a few uses just to have fresh and sharp hex corners.
Last edited by Crankycrank; 04-20-19 at 09:12 AM.