One way to get your own lightboard is to build it, using the instructions and parts lists on this website. The plans here are intended for a chalkboard-sized lightboard. The cost is about $8K, and you wind up with a studio, with really good lighting and really good sound. Most of the parts are easily obtained commercially. For the glass, you will need to contact a local glass company, to obtain unmarred*, and tempered, glass. (No, it can't be plastic. See FAQ.)
However you may prefer to have someone else do much or all of the work! I've worked closely with Matt Anderson of Learning Glass Solutions, and with Kevin Koch of Revolution Lightboards. Their commercial offerings are shown briefly below; visit their websites for more, or contact them directly.
*Getting unmarred glass can be a problem. Large sheets of glass must be tempered for safety, and often the rollers in a tempering furnace leave scuff marks on the glass, especially if the rollers haven't been cleaned and carry glass dust. This normally goes unnoticed; as one glass vendor told me, people look through glass, not at glass. In lightboards however the internal illumination makes any scuffs glow. Learning Glass Solutions and Revolution Lightboards take different approaches to this, and probably have found especially reliable glass vendors. Last I checked, Learning Glass Solutions was using an optical solution, and Revolution Lightboards was polishing out the scuffs. There's much discussion of the glass marring issue on the Lightboard googlegroup.