I believe Heat Amp prices are ridiculous. They're timed items, just like trinket slots and weapon slots, but the only thing they do is double the amount of heat you get per level completed. Not 10x, not 5x, nothing to justify their prices (1 week heat amp costs what, same as 2x trinket + 2x weapon for a month?)
I offer to simply these items:
30 days (because I'm greedy) heat amp, doubles heat. Costs 300 energy. Could be 7 days for 300 energy, but not 2 days for 300 energy, I don't play much.