You can start a cold engine with a priming system even when the engine is very cold, which I've been told is not a good thing to do. Your money would be better spent on an oil sump preheater. During the ND winter, I fly when the OAT rises to +5 or +10F using the preheater(plugged in the night before, cowl plugs poked in front, and a blanket over the top of the cowl for a little insulation) and a single stroke on the accelerator pump. After one pump of the throttle, let it evaporate for 20-30 seconds and then crank. Works like magic.