I'm not the first one to note this, but after having a very successful shopping trip I thought it worth mentioning. Teacher supply stores are excellent places to by game prototyping supplies. I went looking for play money (coins) and found a nice set with all major US denominations. But I also found blank dice dice, a variety of colors and styles of pawns (including 2 inch high wooden ones), and, as a pleasant surprise, blank quad fold game boards. You can also find platic counters in a variety of styles and colors, from the classic cube to stackable chips to dinosaurs and frogs. I will say I found the plastic counters to be pricy for what they were; I couldn't convince myself to spend $18 on a tub of little cubes (500 in ten colors). Per cube, it's not really bad, particularly since you could get several (or many, with recycling) prototypes out of it. But 18 bucks for a bunch of little cubes still seems kinda steep.
Anyhoo, those of you who have not really should investigate your local teacher supply store as a source for bits.
Six bucks for an 18" x 18" board (9" x 9" folded, natch).