I use the white styrofoam for building up mountains on portable layouts, the good insulation pink or blue is hard to find in southern California, I found a great source for the white stuff today when I picked up my kids new bunk beds, the "furniture store" some of you may already have thought of it but i had not until I saw the huge piles around the dumpsters all sizes and a lot of solid squares and rectangles, and some sheets of various sizes and thickness. Next time you need some give it a look
NM
Keeping your eyes open and your imagination working is always a good way to save money. White styrofam isn't as good as construction foam for layout base, but makes fine mountains and such. Even the construction board can be found for nothing or next to it, in abandoned scraps at building sites.
Also try carpet scraps and "rubberized hair" packing for foliage and plants. Is there a thread on the Bach Man's Board for this kind of "hints-and-kinks" wisdom???
Railsider