Head to Crane & Co.
They have some REALLY nice birthday cards that can cost up to $10ish a peice. For all my female friends, I just buy the blank gold or silver engraved birthday cards and stick them in my printer to make a nice custom message. They look really nice and expensive so its definately more then a normal card, but nothing really big.
edit: oh yeah, almost forgot. Are you good with paper? If so, make her a nice set of flowers out of origami paper. They can look really elegant and beautiful if you put the time into it. Personally, I'd do dinner, the card and the origami
Good luck!
-Robert