Eustacia fingerlings are little plastic pets, mostly monkeys but also sloths and unicorns, which cling to your finger, move a bit and make sounds. I think they’d be too young for 11 and 14, my almost 10 year old isn’t interested in them.
I don’t know kind of things your daughters like but Claire’s accessories have a buy three get three free deal at the moment. The Book people are worth checking out for bargains, I’ve got a few things for DD from there. Primark have a lot of Harry Potter stuff, both clothes and other bits, they also have Pusheen things (a cartoon cat) which is a bit of an in thing at the moment.
Mermaid tail blankets have been a big hit for me with teen and tween girls, lots of places do them. Groupon have an offer on a blanket you have your own photo printed on which looks nice too.