As an alternative to wood, you might try mdf, available at any diy store. This is a smooth, inexpensive base material that is easy to machine and paint. Because of its weight. it makes a very stable base for top heavy scenes. Prime it and paint it and you can achieve a finish that looks like wood, metal, stone or just about anything that can be faux finished. Be sure though to seal it as it is a fibre board and if it gets wet will swell and deform a bit.
Its cheaper than wood and comes in 1/4", 1/2", 5/8" 3/4", and 1" thicknesses.
Mike
"Imagination is the dye that colors our lives"
Marcus Aurellius
A good friend will come and bail you out of jail...but, a true friend will be sitting next to you saying, "Damn...that was fun!"