Hi Carter. Welcome to the forum. A little more info about your northern expedition may help us help you. Define cheap? Where do you live? Will you be driving and then setting out on the sled? How much and what type of gear will you be hauling? FYI.....cheap and going to the North Pole don't belong in the same sentence.
It sounds like a utility type snowmobile will suite your needs. Something like a Ski Doo Skandic or a Polaris Widetrack would do well in the reliability dept and carry you, gear and haul a tow behind sled.