Hi,
As far as accuracy goes, light (lasers) are probably the only real way to go. If you search google for Survyer 'total stations' you should get some results from Leica, Nikon, etc... Incidently, Leica manufactures the 'Disto', something I used a lot for floor plans when I was a surveyer, I 'think' its good to 2mm (although some 0.5mm over 300m are available), not the most accurate, but its a start.
What might limit your accuracy is the optics. Leica have always had the best optics, but other companies tend to use complicated electronics to compensate for their poor lenses/mirrors (which makes them a whole lot cheaper). To be honest, I've never attempted to make anything that measures distance, to any degree of accuracy but I think you'll have to take the rise-time of the laser into account, and pulse spreading, also...are you planning on measuring distances 'reflectorless'? by that i mean, are you going to fire your laser to a known target, like a prism, or is it simply to any surface? Because if the surface you're shooting to has a rough surface (1/1000th of an inch) that'll ruin any accuracy.
Hope this helps in some way.
BuriedCode.