Any local farm or tractor supply will have welding cable as well. Heck, there's a grocery store (and farm supply) in Alvin, TX town that carries more metric hardware and welding supplies than all of the local auto parts and big box 'hardware' stores combined.

I was looking for a handful of 12x 1.5mm fasteners the other day and the only place I could find them was the farm supply. Advance Auto, autozone, NAPA, Oreilly, Home Depot all gave me blank stares. crazy.