Expensive, they are made of stainless steel.
They need electrical power to operate. There are two small three phase powered pumps on each one if I remember correctly.
If you do not pay attention, the acid created will destroy a concrete pipeline.
Eye watering, choking vapor emitted. Caution is needed when adding sulfur.
They are still being manufactured, but I do not know exactly where. They were made in Bakersfield, CA. Search for Harmon SO2 burner, a Rocket Shop Cafe will probably come up. That is owned by John Harmon's son, I think. Someone there will know how to get one.