I have three Centurions from the mid-80's that I enjoy very much. One has been my favorite "everyday" bike of late. From the late '70's to the early '90's, Centurions were a popular road bike in the USA, usually among the better bikes in a given price range. Then, Diamond Back decided to "drop" the Centurion name, and put most of its corporate energy into its mountain bike models.
How much a bike is worth depends a good deal on its condition. An older road bike in "like new" condition can provide way more than $200 or $300 in riding enjoyment. E-Bay can be a bit of a lottery, but there are some "winners" out there.