Least expensive prepaid data roaming with an unlocked iPhone in the US Will be travelling to the US a bit and trying to determine the least expensive way to get my unlocked iPhone online.  

My provider (Rogers) has a standard US data roaming rate of $30/mb but also offers travel add-on packs that you can buy for 30 days of usage:

Add on packs are:


10mb for $30 ($3/mb)
25mb for $50 ($2/mb)
75mb for $60 ($0.80/mb)


Alternate carrier options I know of so far:


AT&amp;T GoPhone prepaid service - $20 for 100mb, but you have to be careful not to tell them you are using their prepaid service with an iPhone and you need to muck with APN settings -- walkthrough one, walkthrough two.
T-Mobile's Unlimited $1/day Sidekick data plan - not sure if this is still offered.  Caveats are that T-Mobile will only work on EDGE with iPhone and you need alternate APN settings as well as possibly needing a (paid) proxy to use it


Curious if there are other options out there - I guess it's limited to AT&amp;T and T-Mobile since those are the only compatible (or semi-compatible for T-Mobile) networks in the US...

Here's a wiki dedicated to prepaid data roaming, however it doesn't have much information on US (yet)
My solution was to activate an iPad MicroSIM and use it in the iPhone.  It required a bit of trickery to get it going but worked like a charm - $25USD for 2GB for 30 days

Activating an iPad MicroSIM from Safari (when you don't have an iPad to use): http://modmyi.com/forums/unlocking-activation/712894-activating-ipad-3g-sim-without-ipad.html