I can tell you that right now. Not including transport, assume 10,000yen per day (about $110).
Budget around 4-5000 yen for cheap accommodation in peak season, 3500-4000 off peak.
Lift tickets hover somwhere around the 4500 yen for a decent known resort. These can be offset by multiday passes, but japan isnt a big place for giving out deep discounts on multi day use. Its going to be only a few hundred yen per day saving to be honest.
finally, food... realistically youll want around 1000 yen at least. You can get by on much less, but if youre actually wanting something properish, around 1000 yen should cover you. This is STILL very budget intense. Eating any food on the hill will immediately blow your days food budget
(this can be offset by finding a coupon on the net for the resort youre visiting. They often have meal plus ticket deals for around teh price of just the lift pass on teh door).
If you stick in a single area like hakuba, myoko, shiga kogen or niseko, transport costs are minimised. Im pretty sure you can use the shuttles so long as you have the right lift pass in any of those places. So effectively you only really need to budget for transport to the area and back.
In total if you want to live like a student, then 10,000 is pretty close to the minimum. If you wanna do an ETM and live like a hobo in a car though you can cut it way the hell down.
If you want to live like a grown up in a nice comfortable room to yourself, and getting your breakfast and dinner included, then really youre looking closer to 15,000-20,000. If you want to live like a successful adult, then er... im not even going to pretend ive ever done that. Not only am i broke, im also scottish and like a good Calvinist, I wont be paying extra for a bit of luxury.