Ouch, that's quite a price for data when you can get gigabytes for $10 each.
I'm sure it's not their fault, cell companies love to gouge.
But I thought I'd compare with a couple other options*
Spark: $3 per device with 1MB, $1 per MB
Ting: $6 per device, $3 for 100MB shared
Zact: Requires a Zact device. claims $0 per device, can do 20MB for $1.40 or 100MB for $3.08, shared
* selected arbitrarily on the basis of Ting being an option I've heard good things about, and Zact showing up in search results when I tried to remember the name of Ting