Where do they live? Where do you live? I have bought gifts (hair accessories, jewellery etc.) from Sportsgirl in the past for my nieces and at Christmas time they have quite a good selection of gifts that are quite reasonably priced. But they live in the country with no Sportsgirl anywhere near them so it's a bit of a novelty for them. Might be worth a look though if you have one handy to you.
I also noticed Dotti had a little table of gifts as well, but didn't go in for a look.
Itunes vouchers might also be a hit or if the 18 year old is close to getting, or already has her license, something for her car if she has one?