The $30 plan is prepaid and the activations that come with buying an iPhone from T-mobile are all postpaid. You can't get the $30 plan at a T-mobile store, only from T-mobile online. First step is to get a SIM card.
http://prepaid-phones.t-mobile.com/phone-sim-card
They only offer full size and micro (not nano) SIMs for prepaid. I got a full size and bought a cutter from eBay. You can cut without a cutter, but I didn't want to take a chance.
Then go here to activate:
http://prepaid-phones.t-mobile.com/prepaid-plans
Click the Activate button on the upper right side of this page. Notice that the $30 plan receives little fanfare at the bottom of the page. And, in fact, there are two $30 plans, so make sure you select the right one. If you select the other one, you can't ever change to the one you want. If you tried to activate in a store they will give you the other plan as well as it is the only $30 plan they can give you. You can get the 5GB 100minute plan only online this way.
If you buy a new iPhone and want hotspot, you will have to also select the $15 hotspot option. If you use an older iPhone without the new carrier update you will likely get hotspot free. This you can select later if you want to wait.
Your initial SIM will have $3.34 in credit on it, so you will have to recharge with at least $26.66 to activate your plan for the first month. Again, I'd recommend choosing to get a new number to try it out. Once you are happy you can call T-Mobile customer service and port your VZ number over. When I did it it happened instantly...I was on the phone with T-mobile from my ATT number and it dropped the call (as ATT service was cut immediately) while I was speaking to customer service! I popped in my T-mobile SIM and got a text that my number had changed.
Nice, I actually have two tmobile SIM cards already. Got them for free when they offered free with free shipping just for the hell of it lol. Maybe I'll try out the tmobile service. I honestly don't pay much for Verizon I'm on a family plan with my mom and just pay her 50$ a month for my added phone, I just would like to have my own plan in my name and it wouldn't hurt to have a lower rate as well. I feel spoiled sometimes though with Verizon service I have service literally everywhere I go! Which is awesome lol.