Help Buying a Ford Bronco with some rust.?

Ive been looking for a good bronco and found one with less than 100,000 miles on it. Eddie Bauer, clean inside and out. I'm no mechanic but i know a bit about cars and trucks and i couldn't find anything wrong with it except for rust. Most of the under body was rusted but I'm not sure of any problems this could turn into. There aren't many broncos for sale where I live and most of them have some rust somewhere. Can anyone tell me of problems this could lead to? I think its a fair price (Im not looking to spend a lot) but is it worth buying with the rust?