I don't know if this is available in the US (I imagine so), but in Canada, some companies run promos where you can get $100-$150 gift card for buying a phone and subscribing to their service.
I'm watching and waiting for a good deal. e.g. not too long ago, Koodo ran a deal where they offered a $150 gift card for buying a phone and signing up for their plan. Their plan is contract-free, so if you want to break out from the plan, you merely pay back whatever you owe on the contract. So if you get a phone that they are selling for under $150, it will cost you $150 to break the contract and you own the phone free and clear. Essentially, you would get the phone for free (or small costs). This route would only get you a low-range phone though, which may not be suitable for someone using their phone constantly.