The Arcteryx Silo 40 is a fantastic backcountry ski pack and this one is new, with the tag still on it - it retails for $199. The front pocket allows you to separate your avy. gear and the top pocket is convenient for snacks and extra gloves. The main part of the pack opens in a dry bag style and there is a sleeve for Camelbak or similar bladder. The pack is plenty big for all the necessary layers and gear required for a day ski touring and this pack feels good on your back going up and also on your way back down. Ski‘s can be carried in an A-frame or diagonally and you could probably rig a snowboard onto it but I have never tried. There are also ice ax loops. I had a Silo 40 that I used for two seasons but had to warranty it and bought another pack while waiting for this one to show up - thought I should sell the new pack.
Check out http://www.arcteryx.com/Product.aspx?EN/Mens/Silo-40