What science fiction young adult novel am I thinking of?

[jgrah29]

I read this book a few years ago, and cannot foe the life of me remember what it was called. Here is what I remember about it:

- the cover had a picture of a naked girl in the foetal postion in a bubble
- it was set in the near future (in Australia??)
- Society is very segregated with the rich living in high rise buildings far above street level, and the poor/middle class living on the ground or below ground, not sure
- the main character, a girl, has a best friend who 'dies' in an explosion, and her body is harvested for parts, as is common practice
- because of this, the main charcter decides to sell her body a a rich person wanting a younger body
- the main character then purchases a cyborg body and has her brain transplated into it. This will somehow allow her to get a really good job or something
- The book ends with her discovering that her friend didn't really die, and her brain was put in storage. The best friend gets a cyborg body as well, and the main character gets a job in space travel

If anyone recognises my incoherent memories as a book, please let me know.