C.C.
They make snow boots in tiny little toddler sizes - check on eBay and buy them used! We started taking my kids to the snow when they were tiny, and I've always just bought hand-me-downs online. I think last year I paid $4 for a pair of almost new snow boots. I went to REI and bought their warmest wool socks, and between the boots and socks, I think my kids had warmer feet than I did!
Have a great trip!