I think getting comfortable with bra shopping is a good idea. It's not something that needs to be embarrassing, and can be a really nice bonding experience for you and your daughter. Even if she doesn't yet need one, it can be a "let's just see what's out there that you might like" excursion. Pair it with lunch out.
The less of a "big deal" you make it, the more comfortable your daughter will be. Isn't that what it's all about? Making her comfortable in her own body, with her own sexuality, with her own womanhood? You're the best person to teach her that.
My daughter (nearly 18) and I still go bra shopping together. Do I like ALL of her choices? Nope. They're not to my taste. They don't have to be - they're to hers. She's a jock, so has a lot of (very bright LOL) sports bras, but also has a pretty good selection from Victoria & Aerie. Even if she's the only one to see them (besides me or her brother), they make her feel pretty. I like her feeling pretty.