Direct Buy??? I thought they were a high initiation fee scammer outfit.
My best sources have been the ReHab stores of Habitat For Humanity, yard sales (particularly higher end subdivisions) and close out sales. Knowing that I had a fair amount of places with small 4' X 6' entryways, 6' X 8' bathrooms and 8' X 12' kitchens, I was always picking up leftover ceramic tiles for next to nothing. I'd stick them in my garage until the need arose.
Knowing that I had a re-roof coming up I bought a 50# box of roofing nails for $5 at ReHab store, as well as mismatched (oops) paint for next to nothing.
Where we lived in Houston there were no yard sales allowed except for a HOA sanctioned ($10 permit) once a year. I bought a $2 toilet, a $1 towel rack set and a free sink top and faucet for a 1/2 bath I was adding to a rehab I was working on.
There was also a guy in the subdivision getting ready to do his kitchen and had one or two of his old cabinets sitting outside. I called a buddy who I knew would want them and he got the entire kitchen cabinet set up for FREE. He ended up using them within a couple of months!
Frank