Monthly is $499. 1 year is $499. 2 years is $449. 4 years is $349.
But it depends on the plan. Some plans only allow 2 or 3 years option (online at least). For example, the 25meg+350mins only give 2 or 3 year options. The 200meg data plan you can pick 1,2,3 years. A 400 minute digital 1 rate allows you to pick a month-to-month. Some cheaper plans raise the 2-3 year prices by $100, but most keep the structure in my first sentance...
Some plans are missing - it doesn't seem to support the 25+25 with 350 min plans (i.e., none of the "double data for $5 more" plans).
I tried picking the 400 min digital 1 rate, but then it won't let me pick a data add-on afterwards :(