I know Jo Ann's Fabrics isn't exactly on the normal stop for model railroaders, but if you have a Jo Ann's Etc. nearby, they have some Woodland Scenics products (trees, grass, rocks, molds, etc.) that you might still be able to grab at a discount.
They also have an assortment of clear plastic boxes of various sizes for storing bits and pieces in. And a fair selection of paints useful for buildings and scenery.
Len