Affordable, Homebrewed Optical Networking?

Graham Wheeler asks: "Lately I've been obscessed with grassroots community network projects, and the hardware that enables them. Most sites I have seen focus on wireless RF networking, but I have noticed a few projects revolving around free space optical transcievers. Twibright Labs' RONJA is a good example of what I'm talking about. Not being an electronics hobbyist, however, makes the various plans for building a comm laser from scratch look rather daunting. It seems to me that it would be easier to just make a lens and housing system into which would go one of the many cheaply available copper-to-fiber media converters. Then you could simply modify it so that the laser ports were optically connected to the TX and RX lens assemblies instead of the standard fiber interface. So, what factor(s) am I overlooking that would explain why nobody seems to be doing this?"