Well his heat mat is around 20 cm squared on all day and night. As for crickets I buy them for my other pets and he generally doesn't eat them.. (he is old now) but a pack of crickets is about 3.50 usually and they will last over a month. You won't even feel the effects on the electricity. Honestly. It's about the price of running a lightbulb.
Scorpions are the hardiest things on the planet. They can take any punishment! All they need is a basic heat-mat, 72 degrees is perfect, a really good eater won't go through a box of crickets a month. The biggest problem is mites but regular cleaning prevents that. They don't like getting handled but get used to being picked up and transported. Very entertaining pets! And surprisingly mischevious. 20-25 to buy usually and less than 5 a month on crickets. Do like the occassional pinkey. Really low maintenance pet. Look up care plans before you buy one!