Any Prepaid Family Plan options?

I am pretty set on getting a Nexus 4. The price is amazing, its a nexus, and it will be my first smartphone. I am currently on a family plan with AT&T and we pay around $105 for 1 smartphone and 2 basic phones. We currently have the $30 unlimited mobile to any mobile with unlimited texts also, but that is free for 6 months. So after its all said and done, our plan will be around $125 or so, before taxes and such.

I am just kind of thinking out loud here. So, I can just add a smartphone to my current line and add cheapest data plan (which I think is 20 bucks now), and then we would pay around $145. This seems a bit much, considering we only have 2 smartphone on the 3 person plan. Does anyone out there know any good family plan options? I looked through T mobiles value plans, but they are bit confusing when you have to consider bringing devices over, such as an iphone and a basic phone.

Any help would be appreciated.