I see that, but the prices at indoor parties (depending on the location of course) are sometimes not that much cheaper. I once was to a trance/techno outdoor, that was really cool!! I also don't like dresscode, here it's not that much of a problem. I go with my regular clothes and I don't look like a raver or anything. But I also don't look like a psytrancer, just regular.
I know the Rebirth track, it's really nice but a bit overplayed.