T-Mobile offers its T-Mobile Prepaid 3-In-1 SIM Starter Kit for $20. Coupon code "SIM99" cuts it to 99 cents. With free shipping, that's tied with our mention from March as the lowest total price we've seen. (It's $4 under the lowest in-store price we could find.) It allows you to use compatible unlocked phones on the T-Mobile network and includes a nano SIM card with micro and standard adapters.