I've done quite a few, using just your basic two mirror crap. About $70 bucks for a 50 inch display...
Cons: Does of course darken the picture some, but actually seems to boost the contrast levels.

Pros: Looks good provided you don't have direct sunlight on the mirror, and we usually boost the color temp and brightness a bit. Never had a complaint (yet), only rave reviews. But, again beware of daylight issues... if it is in a drak bar area... should not be a problem at all.
In terms of the other optical pieces you mentioned, well, I'm not Joe Kane --- but that seems like a heck of a lot of money... Heck, buy a sample piece of mirror (1ft square), take it to your shop, set it up in front of the plasma. If ya don't like it, hang the mirror in the restroom!