I recently found out about a source for cheap, long screws. And thought it may be worth sharing here.
When commercial roofing companies re slope flat roofs they remove thousands and thousands of long screws anywhere from 8 inches to 16 inches that just get thrown away.
If you give a commercial roofing company a call and ask they may be willing to set them aside for you. I just got 32,000 mostly 12 inch screws for $100. Which is probably several lifetimes of building pole buildings and log structures for myself.