I built this project using a 6 1/2 hp Honda clone engine with a torque-a-verter clutch. I was going for a modified Jackson Hole Hillclimber look, so I left off the belly pan. The track is 121 inches by 8 inches. The tunnel and bulkhead are scavenged and modified from an old Blizzard snowmobile. The hood is from a factory built Polaris 120 and the seat is reminants from an old ripped seat. The rear suspension is made from scratch and gives about 12 inches of clearance. The front suspension is rigid right now, but I can put the shocks back on, giving it about 4 inches of suspension. I can also put 2 inch paddles on the track, but they would be mainly for looks since it already has plenty of traction. The sled has plenty of power for the kids. It has pulled 3 kids on the tobaggan and 2 on the machine. It travels about 15 mph on the hard pack snow, and can go through as much powdered snow as you want with speeds still faster than I can run through it! The kids love it and have put many miles on it. As for costs, if you had to buy absolutely everything, total would be less than a thousand, but since all I had to buy was the engine, clutch and hood, I spent under 500 bucks. It took a bit of extra time to build the first one (about 20 cases of beer), but now with the pattern and first one done, I can build one in a few days. It was an awesome project, and the kids love it