What are the cheapest unlimited data and messaging iPhone 4S plans?

I'm getting an iPhone 4S soon but my mom wants me to look for the cheapest plans possible that have unlimited data and texts. I don't call people that much so talk time doesn't need to be a lot. I know you might be thinking that I'm just one of those stupid kids whose parents buy them whatever they want, but I'm not. I've gotten good grades for a while now and as a late birthday present my parents are letting me get an iPhone. I don't want the 5 because its too long but I'm totally fine with the 4S. Anyways, thanks in advance. Also, my mom said to look into no contract plans I think. Could you explain that to me?

Thank you so much!

Not sure what country you're in but the cheapest plan for an iPhone in the US, which happens to be no contract, is with Virgin Mobile, which is a Sprint subsidiary. Their plans: $35 for 300 talk minutes, unlimited texts, unlimited data/ $45 - 1200 talk minutes, unlimited texts, unlimited data/ $55 unlimited everything. Note that if you sign up for automatic payment, where the provider takes out the money automatically from your bank account every month, the payments drop $5.So, essentially, you can end up paying $30/ month for everything you're looking for. Good Luck.

Straight talk through Walmart: $45 a month for unlimited Web, text, and talk. It isn't a contract. However, there is an unspoken 2gb limit, so don't go downloading a ton of movies and stuff. But for a light to average user, it works great.