As I understand it, all the US carriers (with the exception of T-Mobile) charge the same per month whether you bought a phone subsidized or not, so it doesn't make too much sense to buy an unsubsidized phone, because you won't be saving anything per month.
I paid $200 for an LG Androidy thing (an Optimus V, if anyone really cares) and now I pay $25 a month for 300 minutes per month and unlimited data. It's a crazy better deal than anything else out there.
This is exactly what makes me sad about a possible takeover of T-Mo. I'm happy to bring my own phone and just buy service, and they give me a discount for that. I may have to switch to a lower quality pre-paid company in the future.