Sadly, the kangaroo purses really do exist and they look about as good as they sound. Happily, Australians don't actually use them. I imagine that the only people buying them are those who will enjoy the horrified response from whoever unwraps them.
With your dad choosing, fashion may be out (otherwise Lorna Jane is a great suggestion for a young gymnast type), so I'll have to agree with the jewellery suggestion. Do you need to specifically say you don't want a hat pin shaped like a koala with an opal in its tummy? Because they're as common as kangaroo scrotum purses in souvenir shops here. On the other hand, tiny opal earings and especially black opals are gorgeous, and a small pair of earrings shouldn't be horribly expensive.