Anyone have any input?
A gift is a tough choice because whatever you decide to do, she's going to over-analyze it 100 different ways and change her mind about your intentions 50,000 times. It could be an ice-breaker, or it could be a thought-out way to torture her by pointing out something she enjoyed is no longer an option. That's disordered thinking at its finest.
Before doing anything, I would highly advise you to read through the "tools" section at the top of this page and work on communicating with a BPD person. A lot of it is counter-intuitive, which is why we all get it wrong at first, and it takes some practice to be able to validate someone else's feelings when they're not mentally stable.
My advice would be to write her a letter, but wait until you're confident that you can do so without invalidating her feelings. We could even help you with the letter here in round-robin style, with several of us adding our two cents from experience.
Whatever you decide, I wish you luck!