HotOtter i agree with everything you have said
OP, YANBU. Whether you spend £2.50, £25 or £2,500 on your DD is irrelevant. As long as she has something to open on the Day and the magic of Father Christmas and the nativity story (if you are christian/believe of course etc etc disclaimer and no offence and so on and so forth) then the monetary value of any gift is rendered totally irrelevant - she already has more than many many children: a loving mother and a safe and happy home.
your friend sounds like a twat tbh, sorry but she obviously has ishoos. quite aside from being a nosey cow! fancy asking someone how much they have spent