Totally get what kai_park means about the letdown. Switching to propane in the middle of a heat treat just kills your rhythm, the whole feel of the metal changes. It's like going from a charcoal grill to a stove burner for a steak. For that budget, you could build a beast of a side-blast forge with a brake drum and some refractory. I ran one for years that cost maybe a hundred bucks in parts.

Nah, you're not alone. It's creepy when it's that smooth. Feels like a copy of a human, not a tool.