press release this morning that simply stated that the iPhone 5C and 5S would be available on Boost starting Nov 8.
According to a Boost Mobile Website the iPhone 4S will also be offered. There's no indication of phone or plan pricing but I expect Boost will match sister brand Virgin Mobile's pricing of: iPhone 5S 16GB - $549.99, iPhone 5C 16GB - $449.99 and iPhone 4S 16GB - $399.99.
iPhone plan pricing will likely be the same as for Boost's Android Phones $55/month for unlimited voice, messaging and data with data speeds throttled to 256 Kbps after 2.5GB. The $55 price is before Boost's Shrinkage which cuts plan prices by $5/month for every six timely plan payments. The maximum Shrinkage is $15 which brings the plan price down to $40 after 18 on-time monthly payments. It's possible that Boost will give iPhone customers a $5/month discount for using auto-pay like Virgin does, but I think that's unlikely. A $5 discount on top of Shrinkage is just too good to be true.
Related: Prepaid Operator Profile: Boost Mobile