Art supplies downtown.
When you work downtown, art supplies can be hard to come by, enter stage left Raw Materials.
They carry everything from sketch books to Sculpey. They have gouache, acrylics, art/technical pens, canvases, pretty much anything you need to get a project going. They even offer framing, though I've never tried them for that.
Plus they're right down the street! If they could get some color copy action, then we'd be talking business!