For my son's first birthday, I had a pinata for the older kids and they loved it!   I wanted the baby's to leave with something, but didn't want to spend a lot of money.  I went to IParty and bought rubber duckies (a pack of 12 was $4 I think).  I made a puddle shape out of light blue paper and then wrote Aidan's 1st Birthday.  It was cute and even the three and four year olds asked for one!

You could also use this idea if you need a cheap baby shower favor!