Both DH and I have big families (each have five siblings), on his side we have about 14 neices and nefews and 4kids to a couple of those neices and nephews. We have a rule, we only buy presents for the people we actually see on christmas day. Which generally only means some of my family who live near us (I refuse to travel for christmas).

I set a budget of approx $20-30 per person (but if I buy some thing on special, so it costs less, but is worth more I just go with that cost). For kids (I only have one nephew here to worry about) I spend between $10-20 - or even less. When DH and I were poorer, we had an absolute limit of $20 per person.

This excludes our own imediate family (ie, me, dh, and the kids) we don't really have a budget for us, as I tend to buy the kids pressies throughout the year (or layby them).