Hit A.C. Moore. Or someother craft store near you. I picked up plastic pillars used for wedding cakes there cheap that fit the maps squares perfect. The shortest ones are the ones I picked up. While there, try the woodcraft section. They have all those little bags of wooden objects. I picked up barrels, tables, buckets, different sized squares, rectangles and cubes. Stack them up so make stairs. Sand down the cubes a bit to make chests. Little more sanding, some paint and alot of those squares and rectangles start to look like shields, benches really whatever your imagination comes up with. I have glued little piles of gold, silver and copper glitter together to make piles of treasure. Just thin white glue with water and it becomes transparent. You can pick up little rhinestones near the glitter or bead section and glue those to the treasure piles. And you will find things you can use in the bead section. The antique looking beads seem to fit in nicely. Try miniature house stuff as well. Again it won't be to scale, but plates, pots and pans are handy. Modeling clay is usefull. ANything you can imagine, you can make. After it hardens go ahead and hit it with some paint. I'm not much of an artist, but with alittle extra time, even I was able to make something that worked for its purpose. Model railroad stuff is good to. You can pick up trees and bushes, you might need to glue them to those thin wooden squares so they stand easier. Alot of the terrain might work as well. I've also used floral foam. Those sheets of green foam used for fake flowers. They glue together easily with spray adheasive, shape easily with sand paper and paint easily with spraypaint.
Thats about all I can think of off the top of my head. When I get out of work I will take a look through my stuff to see what other goodies I have hiding.
Hope these help,
-Gregg