Habitat for Humanity now has ReStores in all U.S. States and Canadian provinces where you can donate used materials you pull out of your remodel: U.S. List
. There are several store locations in most states and provinces. You can take a tax break for donating your materials. They then use them in other projects, or sell in their store. You can patronize them for things you need as well. Using the list you could call or email to find things you need. Our local store was once only open one day a month for five hours, then went to a day a week, and eventually everyday hours. It always looks busy.