I haven't used Mint, but I recommend looking at Red Pocket if you want something more affordable. They have a range of annual prepaid plans from $30 to $360/year, and with most plans, you can choose your network. So, bring your own device, choose the network that you prefer, and choose the plan that works best for you. I've been with them for years.

https://www.ebay.com/str/redpocketstore?_sop=15