Find a mid to late 2000 2 stroke with less than 5k km. Fan cooled 500. 4 stroke engines can have 20k km and be fine. Long track 2up is great. Get a toboggan to tow now before they are all gone, otherwise wait until next year. Used sled prices are almost double what they were pre covid. Sounds like parts are hard to come by so you need a ready to go sled. Educate yourself. Lots info on the net about ice fishing snowmobiles.