I second the motion for a dagger GT, I LOVE mine!!!! REALLY stable, not too hard to roll. It comes in 3 sizes (GTX or GT8.1, GT or GT7.8, and GTS or GT7.5). I have the mid-size one.
Another one to check out is a dagger RPM. that one has a rounded hull so it is easier to roll than the GT which has a planing hull (flat).
The nice thing about those is that she is not likely to grow out of them quickly skillwise. they are both great river runners.
Depending on how little she can afford, she can always get a perception dancer- huge, very long, stable, easy to roll, and you would be able to find one really cheap. but she would outgrow it fast because there have been so many upgrades in boats since the dancer left production. It is a classic. really, a classic! probably hasn't been in production in 10 years or so. I only recommend it if she is looking to spend less than $150 or so for a boat.
If she can afford it, I would definitely go for the Dagger GT, should be able to find one used for $400-600. maybe a little less.
Try out any boat before you buy, there are a lot of different models out there and a lot of personal preference. hope that helps!