Where locally can I find edible lime (not the citrus) in powder form?
You're looking for calcium hydroxide, or "pickling lime", I assume. I believe I have even seen it at True Value Hardware, with the canning supplies, but any shop that has a decent canning section should carry it. I agree that you might find it at Fiesta. IIRC, I have also seen it at Callahan's General Store on 183, but that's been a while.