This situation is not helped by the fact that the carriers have steadfastly refused to standardize on wireless technologies. Even the two GSM carriers (AT&T and T-mobile) have never agreed on the same set of frequencies for data... so eg., AT&T HS(D)P(+) devices (e.g. Galaxy Nexus, iPhone 4) didn't quite work on T-mobile and vice-versa. The regulatory agency (FCC) has basically been either helpless or complicit and maintaining the status quo.
Things might get a bit more competitive with LTE (with more standardized hardware etc.) but there doesn't seem to be any incentives for the big carriers to stop this effective collusion to start a price war. T-mobile seems to be breaking ranks in some ways but I haven't really seen a pricing strategy designed to pull the crowds yet even from them.
The minutes are expensive and no data, but for light usage it's great. AT&T Go phone has the same $100 for 1000 minutes that last a year.
In China, I pay about US$15 every 3-4 months for a level of texting and voice talk that would easily cost $30 / month by itself in the US. (I don't have a data plan.)
I've tried going prepaid (also t-mobile) in the US. The economics worked out as long as I never expected to use my phone at all; if I expected anything, it was a money loss. And even while I expected nothing, I had to keep paying $10 / month so that all my paid credit wouldn't suddenly expire.