Walmart offers the T-Mobile Complete SIM Kit with $30 Airtime / Data Credit for $29.82. Opt for Site-to-Store pickup to avoid the $4.97 shipping charge. That's $10 off, tied with our January mention, and the lowest price we could find. (For further comparison, the kit is available for $5 elsewhere without the minutes.) It includes one SIM, adapter kit, and $30 in credit for data and talk minutes.