Cell Phone Store

I want to open a store cell phone, something like Metro PCS and Boost Mobile and T-Mobile
How much money do I invest?

One of my friends (trading partners) wanted me to share with him in a cell phone store retail (Boost Mobile) ... It was eight months ago ....
The study was complete and the plan of 15.000 to 20.000 (location of Nice and decent store) ...
Well, I did not, he went himself .. and as my opinion, it was just under $ 15,000 ........ (It make decent one) .. As I know there are a good money out of him .. all companies (other than cell phones) that are barely surviving including mine ..
So good luck and hope that this information would be useful ..
Good day ..