1. First things first. If you are in a contract with a service provider, I would suggest to rid of of the contract. I believe any service provider is giving Iphone 4 in contract right now, because all the service providers are upgraded to Iphone 7.
2. I find 'simple mobile' provider is giving good offers such as $25 unlimited talk and text. The other offer is $40 unlimited talk , text and 4 GB data.
3. You can shop around other providers such as H2o wireless or boost mobile. Surely, you will get a better deal than what you are paying now ($65)
I hope this answer would help. Thanks.