I worked on Gravity Probe B at Stanford, and Robert is absolutely right about the immense pickiness of high vacuum equipment.

However, much of this exotic design is to avoid contamination of the ultra-high vacuum environment (much higher vacuum than in Earth orbit, believe it or not). Building equipment to simply survive the environment in Earth orbit is much easier, and many standard materials will work just fine if you know the ropes (one small example: cadmium plated screws are right out.) The Russians have built working space equipment using much less exotic systems, but some of these suffer from reliability problems like electronics. I think the correct design philosophy is somewhere between Russia and NASA.

Oh, by the way, unlike a space habitat, something like a space telescope that needs high optical tolerances does require some fairly exotic engineering.