You might look to companies that install billboards. They have large pieces of
billboard tarps for little money. Since they have been painted, or can be painted,
they would make an attractive porch covering. I got mine for under $20 for a heavy,
15′ x 20′. If you wanted, or have someone willing, you could overlap glue different
painted ones together to make a great design and even include some clear vinyl for
windows and screen for doorways. Lynda, Pensacola, FL
Tiny House Ontario 
You might look to companies that install billboards. They have large pieces of
billboard tarps for little money. Since they have been painted, or can be painted,
they would make an attractive porch covering. I got mine for under $20 for a heavy,
15′ x 20′. If you wanted, or have someone willing, you could overlap glue different
painted ones together to make a great design and even include some clear vinyl for
windows and screen for doorways. Lynda, Pensacola, FL