Many of those Schwinns (and if my info is correct, at least some of the Centurions) were made by Panasonic. The Panasonic branded bikes are themselves well worth a look. I have a 1988 DX-3000 and it's a great bike that I picked up for a pittance.

As far as the Centurions go, they do have a great reputation and I don't doubt that it's well-deserved; but in many markets they are very sought after and not likely to be flying below the radar.