How much data do I need for the iphone 5?

I currently have the iphone 3gs and a data plan of only 500 mb a month. According to my billing the most data I've used on my 3gs is 300 mb, averaging only around 100-200 mb. I don't use my iphone for streaming, just e-mail and basic browsing and minimally facebook. It's normally on Wi-Fi most of the time. However, I head the LTE network goes through data like crazy. Should I get more data or would 500 mb be enough when I upgrade to the iphone 5?

No 500MB should be enough. Simple things like Email and basic browsing don't take up much at all.

LTE is faster, yes, but other than the fact that you can do a whole lot more over LTE, it doesn't consume any more data than 3G, and so you shouldn't use a whole lot more data when you have an LTE phone.