These two quotes sum it up pretty well, in my opinion.
I started with a cast iron pot over a Coleman stove. It was uncomfortably hot, even wearing gloves.
I couldn't justify the cost of an RCBS Promelt, so I bought a brand new Lee 4-20. Wow, I could now cast in comfort. It dripped a lttle, but no deluges.
I stumbled across a Promelt at an estate sale for $80.00, now my Lee is the back up, and only used for casting snagging sinkers.
I did buy a thermometer, I really don't think it is necessary for 90% of the boolit casters, same with a hardness tester.
Robert