I use this one:
http://www.amazon.com/Maxi-Matic-ESB...4119010&sr=8-1
and it gets plenty hot.
Main reason I like it is that it has a
solid plate top made of cast iron instead of the heating coil. Heating is much more even than the coil burner type.
I don't cast, but I can tell you the cast iron plate will glow dull red on high which should suffice for your needs.