The best thing about habitat for humanity stores are their dumpsters! Many of them are happy to let you dig through them because the less in the dumpster the less it costs them at pick up. You can find doors scrap wood moulding etc. a leftover piece of moulding can make a great picture frame! I have a friend that built a green house out of bits from their dumpster and another that built a small shed out of doors from the dumpster.