Snowmom, you can go to UPZ Site Dan the distributor is based out of Osoyoos BC and sells Snowpro bindings that would be perfect for you kids, also there is no duty on the stuff because it ships from Canada. He also has boots too. Drop him an email.
If you want used bindings and can wait untill next season, go to the Canadian Ski Patrol Ski Swap in the fall, there should be some used carving gear there.
IIRC Fanatyk in Whistler sells alpine stuff too. And even check out Prior's shop, I am sure they have some stuff kicking around.
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You might have to ask at the shops, because they sometimes dont stock it on the shelves. I went to Banff and asked if they had plates, they did in the back. They are stocked for the snowboard race teams that train there early season and need spare parts.