Just to compare, all prices in US:
Up here in Canada, sodium hypochlorite is on sale at the corner hardware store at $4.92 US for a 5 liter (1.3 gallon) jug, so that's $3.78 a gallon.
Cal hypo at the local pool store, their house brand, is on sale for $49.35 for 18 kg (39.6 pounds) so that's...