Mine are 4 and 7, and we spent about 50-75 each (I don't have exact numbers in front of me).
It was quite low, lower than usual, because:
1. They wanted the same thing from Santa and it was only 35$ joint gift.
2. My mom had given me a ton of art supplies that I used for DD's gift.
3. My MIL gave us cash and asked us to shop for the kids, so we got some things off their lists, rather than the usual junk MIL buys.
I am planning for this spending to go up quite a bit over the next decade. They'll be wanting more expensive things pretty soon. But I'm going to enjoy these years when their favorite present is 5 rolls of scotch tape!