How to find cheaper and better home remodeling materials than the big box stores?
You won't find any cheaper. You may find an item or two at your local lumber yard that are less expensive but in the long run, the big box stores can sell cheaper.
You can't find it cheaper, the big box stores make less margins, so the small local chains can't compete
you can check saw mills for rough cut lumber
Habitat for humanities has resale stores & other charity stores have building supplies. Here in phoenix we have 3