The local co-ops bag 0-0-60 up here for ice melt, so it hasn't been hard to find. Potash (0-0-60 or KCl) is the fertilizer form of potassium. If you are truely desperate to find some, there are water softener salts are potash (usually advertised as no sodium salt). Potassium metal is highly flammable in water, so its not a good idea to use pure potassium.