Many PhD programs offer full funding such that you never even have to think about tuition. The UCs can be difficult and often don't guarantee it, but I think most PhD students there are not paying tuition, either. Often when you are offered admission there will be a funding 'package' where you will be offered a mix of TAships and fellowships; even in the current dire economic climate, I think you are very unlikely to expected to bear the whole cost yourself. PhDs are labor for the university at least as much as they are students, remember.

I only applied to fully funded programs in the US because I knew that I wouldn't be able to pay any kind of tuition, which is how I ended up at a private university; I know it gets more competitive every year and it's all pretty much a mess, but there are still a lot of programs that do this and it's worth taking into account.