If you do go off the beaten path and away from the big 3, T-Mobile, Verizon, AT&T and don't get unlimited data you can seriously save some money by going with a smaller company. They use the same towers so you get the same service.
I won't say which one I got because I don't wanna shill for a single small provider, but I was with one of the big 3 and was paying $45/month for a single line, unlimited talk and text and 2GBs of data.
Then I switched to a smaller one, one you hear about on podcasts ads for example, and now I have the EXACT same service but only pay $21/month. So that saves me $24/month or $288 a year!
The downside is you can't lease on the cheapest plans so you have to buy the phone outright and they don't offer discounts on new phone purchases when you wanna upgrade in a few years. But if you are saving $300 a year that's fine with me.