When signing up for wireless service or changing carriers, there is typically an out-the-door cost associated. T-Mobile wants customers to have a true $0 out-the-door experience, and in order to do so, it is now offering a finance option for its Equipment Installment Plan (EIP). EIP Flex 36 lets you finance the device, taxes, and fees at checkout over 36 months at 0% APR. Both options are available starting August 6 (this Thursday). That brings your monthly cost to about $3/mo when financed.