Just thought I would tell you guys this bit of info.
This will only work if you're out of your one year contract with Sprint. (As far as I know, and still YMMV)
So, if you're like me and have been wanting a new cell phone for a while (not to mention a new plan) but don't like to shell out the $200 for a bright shiny new toy:
I'd really been looking at the T-mobile deal on Amazon. I called Sprint (888-211-4727) to enquire about cancellation. (If you get to the point where it asks you to state your business, say "Cancel Phone", it'll put you right through. ) Filled them in on all the details and they offered me $150 credit towards a new phone, one month free service and 750 anytime and unlimited nights and weekends for $40/month. (this doesn't include their Vision plan, I got it free for the 1st 3 months after that it's $10/month). I asked if I bought a phone seperately (from CostCo) if they would apply the credit to my bill. They said that's fine.
So I now have a new phone that's awesome (I got the A500 personally) and a great new rate and no bill for 4 months. I did of course have to agree to another one year contract.