I just did a quote on the Verizon website for 2 iPhone 5 16GB with 1GB of shared data, unlimited talk, unlimited text. It is $400 for the phones and then $130 a month.
If you went with the iPhone 4 or 4s the phone would be free but you wouldn't be on the LTE network.
All of those options would require a 2 Year contract
There actually is one cheaper data plan but I ignored it because with an iPHone I have to think you'll use at least 500MB each a month. (1GB total)
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If you went with one of the Prepaid Phone plans the first difference is you'd have to buy your own phone up front. I don't think you can use the iPhone 5 on any of them yet --- you'd have to use the iPhone 4 or 4s.
The cost would be $55 each ($110 total) on the PagePlus plan (2GB data, unlimited talk and text). PagePlus uses the Verizon network. Right now the iPhones aren't officially allowed but there are scores of people who have activated their iPhone 4/4s devices on PagePlus.
Or $45 each on Straight Talk ($90 a month) (ATT network) Straight Talk advertises unlimited data but in truth they throttle the phones down when you go over 2GB.
The HUGE advantage of these prepaid plan is the no commitment/no contract aspect. You pay for your own phone upfront but you can cancel or leave at anytime.
A good place to research is
http://www.howardforums.com/forums.php