Virgin Mobile has the most bang for the buck that I could find. We've got three.
Their deal is $60 for the phone, including $20 airtime. Rates are .25 per minute up to 10 minutes daily, .10 thereafter. Anytime. Free email, free voicemail - which do not count as airtime .
Refill cards are $20 & up, and are good for 90 days once activated. This is the best going for low-usage users like my wife, who has yet to use up a refill before it expires.
BTW, if you order it direct from them it looks like you'll get a bonus $20 airtime, but I've seen that deal in-store also at Best Buy.
<edit-added>
If you go to their site, the products page only shows the two more expensive models. On the right menu, under phones, click on "Kyocera Party Animal" for the $59.95 package.