Hi. I love the Bare Minerals line and I wish I had access to this makeup at a teen. Yes, it may seem expensive at first, but when I wore the liquid makeup, I used a drug store brand (Almay) and used 2 $12+ bottles in the amount of time I use one $25 pot of the Bare Minerals. I also had to cake the liquid on to "hide" the pimples it caused. My skin looks better now than it ever has--and I've been diagnosed with Rosacea. Bare Minerals is so healthy.
If you have access to a boutique, you can schedule a "make under", but to make sure your daughter has plenty of time, try to do this during the week and avoid weekends--boutiques are crazy on weekends. I'm sure Sephora can help as well. I've seen some very good sales assistants at my Sephora. Make sure the make up artist shows her just how little foundation to use--it is surprising how little it takes for coverage. If it looks cakey or powdery she has used way too much.
The starter kits are good values since you get the application brush(es). You do need brushes designed for mineral makeup. If your daughter has any skin breakout problems, please consider getting her the Blemish Therapy. It is wonderful and clears up a pimple in a day or two!
If you are interested in eyeshadows, there are a few kits out for the holidays that have mini (half-sized or X-small) eyeshadows. These allow you to try some colors at a lesser cost. Some people pick up eyeshadow colors and even foundation off eBay, but I get a little wonky about purchasing makeup second hand. It would be OK as long as the product is sealed, but it skeeves me out.
QVC is currently offering some special returns through the holidays. If you order a kit and she doesn't like the makeup or it irritates her skin, you can return through the end of January. One nice thing about QVC is many of the products have customer reviews. You can also get reviews off the makeupalley forums.
She does need to be color-matched in person. As a teen and especially if she is fair skinned, the radiance colors make nice blushes. One nice thing with Bare Minerals is that they are safe to wear all over the face. So you can take the radiance and use it as a blush, as an eye shadow and even dip a lip balm in the powder and use it as a lip color. It is very multi-tasking. As I said you do need the recommended face brush for the foundation (comes in the kit) but for eye colors, I've found the CVS Essence of Beauty line of brushes good quality and affordable. I hope this has helped in some way. Good luck.