It is very useful to look for people with similar profiles to you on the past profile threads and see how they did. Here's the 2012 thread: viewtopic.php?f=3&t=4274
. Just remember that most of the posts will come from the top students, so it's not a representative sample of people you'd be competing with.
A piece of advice would be to apply for astronomy departments that also study cosmology. I guess what I really mean is that sometimes cosmology people will be in an astronomy department, and sometimes they are in Physics so make sure you are widening your search enough to include both programs. At some schools, one of the departments may be lower ranked and thus easier to get into, but you can still benefit by working with the cosmologists in the other department.
My profile is pretty similar to yours -- my GPA is a little bit higher than yours but we will have about the same amount of research experience. I'm not sure about your publication record or how well your LORs will be so we can't directly compare. However, my GRE wasn't that great -- 44th and 53rd percentiles. I was applying to astro and planetary science programs, and for the schools you mentioned, I got rejected from UC Berkeley Astro but accepted at Cornell Astro. I should mention that I'm an international student so private schools were more inclined to accept me than public schools. You can see my profile in the above link for more details.
But based on my experience, I think while no one is ever guaranteed to have a good chance at the top schools like you mention, you are definitely within reach and you should apply to them if you find people that match your interests. But, like all applicants, you should apply to a range of schools.
Another piece of advice though is to use your supervisor from this coming fall (experimental dark matter at UCLA) for your 3rd LOR instead of a prof of your classes. A LOR is supposed to highlight your ability as a researcher -- your transcript is good enough for showing that you are good at classes. Having the 3rd LOR be a lecture prof is OK but since you have a research option, it will really strengthen your application.