IDK about 1x2 sections, don't they move around a bunch; about the only problem with the ROB board (bulk and wieght aside) is that those little clasps are worthless and the board can slide and move.
I make a lot of terrain out of that polystyrene sheet insulation
(so you know what to look for at the hardware store
), and I'm currently sitting on a panel and a half of the stuff, slowly contemplating what kind of board I want to make (volcanic, craftworld, icy, so many choices!).
I did previously forget to mention the foam stuff, you even have two options; a thin sheet of foam glued to thin pieces of plywood, or simply use the thick sheets. I can only find 2 or 3 inch thick stuff out here, I moved from Missouri where I could find 3/4 inch thick stuff (which was awesome), but I've usually found it for $15 a sheet, I don't recall the demensions, but I know that I'll need 2 sheets to make a 4x6 board.
I'm aware of no company that makes a comparable product (e.g. modular gameboard), so as far as I know, you can fork out $250-$300 for the ROB board, or a probably a third of that making it from scratch from foam and whatnot.
Again, Meganb, if you want PM me and I'll be happy to talk to you personally about making one of these (or anybody else for that matter).