Be advised the $3.95/mo option isn't actually paid by the month. That's what it breaks down to, but when you read it, it's the 3-year plan and you buy all 3 years in advance (its listed as $142.20 to sign for 3 years at that rate).
There's no way to do a pay-as-you-go on the 3, 2, and 1 year plans. The month-by-month is $6.95, just so you have some comparison.