Replacing roof on tiny trailer

O.K. So I got the trailer home. And now 2 weekends into it, I have it completly gutted. I got a couple of pleasent surprizes. There is a fairly new water pump it it and a 20 gallon water storage tank that I didn't see when I first inspected it.
However the roof needs major work. It will be an easy job but I want it to last. I would like to just replace it instead of repairing it. It looks to be the original courragated sheet metal. Don't know if it is aluminum or stainless but it is only about 30 guage at best. Very thin. I want to replace it with a good product with out breaking the bank. I am not looking for the "cheapest" but something in the middle. If it is wood with a waterproofer or back to thin metal. I can work both media. What have you experimented with and list pros and cons of both.
However the roof needs major work. It will be an easy job but I want it to last. I would like to just replace it instead of repairing it. It looks to be the original courragated sheet metal. Don't know if it is aluminum or stainless but it is only about 30 guage at best. Very thin. I want to replace it with a good product with out breaking the bank. I am not looking for the "cheapest" but something in the middle. If it is wood with a waterproofer or back to thin metal. I can work both media. What have you experimented with and list pros and cons of both.