Good cellphone companies that have iPhones?

I want the iPhone 4 but not willing to pay over $90. I already tried Verizon they want to charge me too much and so does at&t. I have T-Mobile right now. I want to switch because I can't get an iPhone and I have a terrible signal. Can you name companies who have IPhones?

AT&T has the iPhone, but the cost (and coverage) is similar to Verizon's.

Sprint has the iPhone, and before taxes, one line is $80 per month. The problem is that Sprint has poor coverage outside of bigger cities and main highway areas.

There are prepaid options that are in the range of $50 or less a month, but you must buy the iPhone outright first to use their services.