Sorry, Virgin Mobile's offer for the Basic Rate plan, also known as Pay As You Go, expired as of Jun. 24, 2013. The Basic Rate plan is no longer available to new customers nor to current customers wishing to switch plans.
Current customers with the Basic Rate plan active in an account will be grandfathered and can keep the plan until the plan is discontinued as long as they don't change plans or let their accounts expire. If a current customer with an active Basic Rate plan changes to a monthly plan($20, $30, or $40 per month) the Basic Rate plan will no longer be available to them.
But don't despair. Virgin Mobile Custom and Walmart are teaming up on new plans and phones: