I don't really know help though

Ok so my mom has had every iphone and she has and iPhone 4S and she is giving it to me but she has had AT&T and i know that is really expensive does anyone know how much it woul be per month. She has the iphone 5 now -random. But if so is there any other company that is cheaper and i know i would have to have it unlocked it something like that

First you need to iPhone Factory Unlock your phone first and then check with different carriers the plan you wanted to get. There are a lot of affordable plans on TMobile but it really depends on your needs.