I have about $300 dollars in materials for the fiberglass. I bought the Fiberglass cloth on sale as it was the last 20 yards on a bolt, I think it was something like $2.85 a yard. I am also using a store branded epoxy which is much cheaper, like $75 a gallon. I have had to buy a second Gallon as it looks like the first gallon is not going to finish the project. That all said , I'm not sure it will be cheaper as I also have to purchase paint to provide the UV protection needed. I think it may be more labor intensive too. The amount of time I have spent on the roof alone I could have skinned and trimmed the whole tear and I'm not finished with the roof. My reason for Fiberglassing vs Aluminum sheet is I want to make sure there is no water intrusion. Plywood boats use the same process to make them water tight so I figure this should work great a I do not plan to submerge my tear. I have no plans for any trim as this would require penetrating the fiberglass.
Jason