Just going off what I overheard between my two kids over christmas. DD1 works a full time job and is 27, (as this is about money) she earns about £50k. DD2 is 22 and in the final year of her languages degree, has no job and is a 'broke' student, but scrapes by.
I think they spend about £70-80 on each parent for christmas. They split the cost down the middle, as it is a joint present. DD2 was a bit disgruntled and said to DD1 that it wouldn't hurt her to pay more than half as she is actually working.