One of the problems with the way phones are bundled with plans is that your rate doesn't drop once the phone is paid for (is out of contract). Prepaid phones are an answer - some carriers have (much) lower rates if you already own the phone. Here is Virgin Mobil's for the iPhone.
VM is basically Sprint service, so if that works in your area you can save a bundle compared to Verizon or AT&T over the life of one of their contracts.
I hope this pushes companies to lowering their plan rates once you are out of contract... but somehow I doubt it.