First of all -- what a great kid you are. Your mother is lucky to have someone who wants her to be happy.
As for the machine, it's probably too close to Christmas, but do think about garage sales, craig's list, and ebay. You can get a good deal and, even if the machine needs a little work, it may end up being better -- and a better deal --than a brand new one.
Wish we could all be there on Christmas morning!