Many years ago, when my youngest son was about 6, his class was asked, after Xmas, to draw a picture and write about their favourite present. Out of all the presents he received he chose to draw & write about his magnifying glass, that Santa had bought for around 50p! Under the age of around 5 I don't think children have much idea of the cost of their presents. I have 7 grandchildren (so far), and when a birth, birthday, Christmas comes around I ask the parents if there is something the child needs - bedding, clothes & other 'boring' but necessary things. I then buy it ( or contribute if it is something very expensive), and also get the child something I know they will enjoy - sticker books are a favourite! For older grandchildren I have put together boxes of craft items & invited them around to have a crafty day - great fun for me too!
I know that Marwell Zoo has "Zookeeper for a Day" events. I would think this is something most of the larger zoo's offer.