I've seen something around a 64G if my memory serves. I seriously doubt your friend has anything that size, though. Besides the fact that they almost always go by 8's, anything above about 8G started getting outragously expensive.
http://www.tigerdirect.com/applications/searchtools/item-Details.asp?EdpNo=2074958&sku=I46-2060
Yup...more than my computer... MUCH more...