I bought the 7" galaxy tab for my kids. I think u can get them as low as $190 sometimes.
The good thing about it is that you can have a micro sd card for additional storage, so you can have heaps of apps plus load her favorite movies on as well.
I looked at buying the cheapies but the memory on them was so low that you wouldn't be able to do much so it was pretty pointless.
The other one I looked at was the the Google Nexus which looked pretty ok too.