The constantly changing landscape of the 3rd party mobile data market (more like underground) makes it impossible to answer this question today and have it be accurate tomorrow. Staying on top of all of the changes is a full-time job. Luckily, the Mobile Internet Resource Center does just that.
We VERY highly recommend the MIA (Mobile Internet Aficionados) membership in the Mobile Internet Resource Center. Check out the Full Blog Post here (with DISCOUNT CODE!). They maintain guides on the latest plans available. Note: We are not affiliated and make no money from recommending their membership. We just believe it's well worth the money to have someone else track this and provide alerts when new plans come and go. Of course, their site is also a wealth of information on EVERYTHING mobile interent.