Such costs are all over the map. When we were overseas in South Korea you could get a MiFi (mobile wifi) device for cheap and a good price for the monthly fees. You'll have to shop in your town to see what these cost and then you should be able to pick your solution.
It would be too much to ask for a world wide answer with countries and states as well coverage in this small space.
Some new members forget to add details that help narrow the question down.
I currently have a 1st gen ipad (with 3G) and an iphone 5. I spend a lot of time in the car and I only listen to podcasts using the TuneIn Radio app from the ipad. I sync both the ipad and the iphone to the car's Bluetooth, because I want to keep each device's audio independent.
Here's the question: I want to give the ipad to my daughter (since I only use it for Internet radio in the car), but want to still have a device that I can get Internet radio via cellular data. I considered the ipad mini, but I first wanted to see if anyone had a suggestion for a cheaper solution. From what I could find, there aren't many options other than the ipad.
Thanks in advance for any help!