The email use will be nothing, it really comes down to the streaming bit. Do you have an iPhone or any other smart phone. If you do you should see how much data you typically use in a month on that then make your decision accordingly. For instance I use my iPhone a ton, but find myself on WiFi most everywhere I go so in the month of July so far I have only used 682MB. I only have a WiFi iPad so I can't say for sure but I would imagine my usage would be even lower than what it is on my iPhone. Hope that helps a little.