If I want to use the iPhone 4S on T-Mobile's network I am stuck using edge only because of incompatibility between the GSM networks (thank you FCC!) and which bands are available to whom.
If I were to want a plan with AT&T that offered me what I have now (450 minutes a month, 2 GB of data and unlimited texting) I'd still be out 90 USD per month whether I purchased my own device or not because AT&T doesn't do discounts for bring your own device customers (T-Mobile contract customers can get a discount for bring your own device, or at least that was the case when I was a customer with them. Knocked $20 off the price off a contract).
I'd be more than happy to purchase a phone outright and pay MUCH less per month.
My sister has an unlimited data plan, 400 minutes a month and unlimited texting for a grand total of 40 EUR in The Netherlands with T-Mobile. She doesn't talk much, but texts and iMessages a crap ton and uses about 6 GB's of data on average listening to streamable music and online radio stations. At the current exchange rate that is 50 USD. Do note that her phone is subsidized as well, also it comes unlocked so she can move carrier when her contract is up without issues.
I recently canceled my AT&T contract, paid my ETF, bought a straighttalk SIM, and now $50/mo ($45 plus taxes.) for 'unlimited' service. It works without unlocking because straighttalk is an AT&T based MVNO (or at least the sim I bought from them is.). It's not perfect, but I'll make back my ETF in four months.
You might be on the AT&T cell network, but you're being proxied onto StraightTalk's gateway to get out onto the Internet. And that's the part which sucks. :)
T-Mobile is retooling their network to give HSPA+ speeds to iPhone users. This should be done by the end of the year. I am considering leaving Verizon for their bring-your-own device plans with my iPhone 4S. These plans are around $45/mo for 5GB data and more voice and texts than I can use. The only thing holding me back is their insistence on getting me to sign a 2 year contract. I've been on Verizon for 10 years and know nothing about T-Mobile's level of service. I would not want to lock myself into a contract with them without the ability to leave at will.
> T-Mobile is retooling their network to give HSPA+ speeds to iPhone users. This should be done by the end of the year.
According to the t-mobile reps I spoke to, their refarming project will only be finished in a few cities by the end of 2012 (LA allegedly included, although in the past t-mobile reps also promised this would be done by September so YMMV). The nationwide project will take all of 2013, so don't hold your breath. I'm about 30 days away from dumping them and going with Straight Talk.
I use that plan right now. It's pretty nice. 100 minutes is a little short for me, but it's $0.10/minute after that. My first two months' bills were $33 and $35, even with the minute overages.
There's no plan on that page under $50/month. And the $50/month plan (which I currently have) includes first 100 MB (!) at 4G, after which the data is at 2G.
I have a prepaid mostly-data SIM for $30/month via T-Mobile prepaid (http://prepaid-phones.t-mobile.com/).
Maybe we'll see more consumers move that way around Google's (rumored) November 5th phone launch.