C.F.
My husband's family does a "little family" Christmas that consists of us (2 adults/6 kids), his sister (1 adult), his mother and step-father and we exchange gifts between all of us. We usually do this on Christmas Eve. Then on either Christmas Day or Day After depending on everyone's schedule we do "big family" Christmas which is all the siblings for my hubby's mother and their families so there will be aroudn 50 ish people. For "big family" Christmas the adults (anyone who has graduated from high school) draw names and then everyone buys the children (high school age and below). Now granted their is no actual $ amount set but people buy according to what there budget will allow and it has never been an issue in the 7 years that I have been a part of this tradition. There is one family that some years participate and then other years opt out of participating if it is financially too tough.
Hope that helps.