The "best plan/price" depends on how you use your phone:
Just talk - Page Plus:
Page Plus $80 for 2000 minutes good for 1 year. No monthly charge. If you run out of minutes, just buy another card.
A little talk, a little text, a little data - Page Plus:
$12/mo. for 250 minutes/250 text/MMS messages/10 MB of Data
Unlimited 3G - talk, text, web, 411, IM & email - Boost Mobile:
$60-$45/mo. for Blackberry phones
$55-$40/mo. for Android phones
$50-$35/mo. for Other phones
Plans start at the highest rate then shrink by $5 every time 6 payments have been made on time until you get to the lowest rate. See
website for details.
Unlimited 4G - Sprint Everything Plus:
Their cheapest plan is $59.99/mo. for 500 minutes with unlimited 4G data.
They also offer discounts on other Sprint plans too (Individual, Shared, Mobile broadband).
Instructions
here.