Graduation Party Friendly Gift... HELP ME!!!!?

i have this friend... who i like... and she likes me... but we aren't like best friends or anything... and i used to take voice lessons from her mom... and i'm also friends with her sister... but we both graduated this year... and she's having this graduation party... and i have no earthly idea what to get her. the only meaningful gift i ever remember her telling me she received once was a completely metal-free necklace because this other friend remembered she said she was allergic to metal... but that's about it. i know she likes musical theatre... and dance... and that's pretty much it. what should i get her? it doesn't have to be anything big (like my mom always gave graduates towels in their school colors) but i want it to be something that says "even though i didn't get to know you THAT well, i still think you're a wonderful friend." so i don't want it to be just anything. but any ideas are appreciated! what should i get her!!! help?? (i'm a girl btw, if that makes any difference)