Replying to Sleds

so not necessarily a ski gabber topic, cause i am talking about snowmobiles, but back country skiing involves them so i am taking a shot. trying to get my hands on a good BC sled. i know a lot about engines and motorcycles and stuff but pretty clueless when it comes to snowmobiles. From what i have found out, when dealing with powder and stuff (which is what will be the main focus) its best to have at least an 800, with like a 151 track. trying to not spend more than like 3500 bucks but could be flexible. any advice?