After the big scare this thread put in me, I raced down to my local Home Depot and bought a "lead foot", i.e. one foot of sheet lead off a 12" wide roll of .040 (+/-) roof flashing. It cost me about $2.00. Apparently the disappearance of sheet lead is a local issue.
Home Depot here had nothing but vinyl flashing. Said to try Bass Pro. Sigh.
I ordered my lead from McMaster-Carr. 25 lb, 10 square feet for about $69 including shipping.
Amazing you can get sheet lead in California (where you just about can't smoke in your own house) but not in Ohio or Indiana.