T-Mobile 4G $30 Plan SIM Card

I have been using the T-Mobile pay as you go plan for many years, I am planning on getting a nexus 4 and decided to go with the 100 min unlimited data. I still have about 50 dollars in my account. Is it possible to transfer my balance and number with a new Sim card ? If so should I activate online first and then call customer service.

Nope. 100min prepaid plan is for new activations only.
 
What is the cheapest way to get a sim card for this plan?
The one that Walmart sells is something like $14.

Also the plan refills state that [from:walmart.com - Walmart]
The $30 Unlimited Web & Text with 100 min talk plan works only with T-Mobile Phones purchased from a Walmart store or from Walmart.com."

Any help would be appreciated.
 
lots of variables at work here. if you had a device that is, say, more than a year or 2 old, you might simply go into a Tmo retail location and ask them if they could update your SIM to the latest one - tell them something.... you're having trouble with 4G or such.
I got two like that, and I'm one of the cheapest customers they have....
But maybe the better question, to your point, is "does the WalMart special include a unique SIM not available anywhere else"
to which - I dunno..
What is the cheapest way to get a sim card for this plan?
The one that Walmart sells is something like $14.

Also the plan refills state that [from:walmart.com - Walmart]
The $30 Unlimited Web & Text with 100 min talk plan works only with T-Mobile Phones purchased from a Walmart store or from Walmart.com."

Any help would be appreciated.
 
What is the cheapest way to get a sim card for this plan?
The one that Walmart sells is something like $14.

Also the plan refills state that [from:walmart.com - Walmart]
The $30 Unlimited Web & Text with 100 min talk plan works only with T-Mobile Phones purchased from a Walmart store or from Walmart.com."

Any help would be appreciated.

Your questions are already answered at the beginning of this very thread.