Look on the Australian Geographic online store - select gifts for kids in the age range you are after and sort by price (lowest to highest).
Sticker books are always a hit with my girls. The crayola wonder pads are around $10 I think. Can usually get a small plush soft toy for under $10 too - that would be a hit with the 3yo, I think.
I think the felt boards would be better for the 5 year old (less likely to lose the felt pieces and more likely to use it properly).
My girls would be happy with a $2 scrapbook and some stickers from the $2 shop.
Edited by YodaTheWrinkledOne, 05 December 2012 - 01:51 PM.