well biked

Here's a link to Sheldon's site, with info on the '84 Centurion product line, including a model called the Lemans 12. Not sure what the difference is between a Lemans RS and a Lemans 12, or what year the bike you're looking at is, but FWIW the Lemans 12 appears to be a mid-to-low level bike. You said in the original post $200-300; no way the Lemans 12 in the '84 catalog would be worth nearly that much, even in excellent condition. More like $125 in excellent condition (depends on market conditions in your area of course, but that would be close to the average I think), much less if the bike's paint isn't good, the components need work, etc.

www.sheldonbrown.com/centurion1984/index.html

Check out the catalog page for the Lemans 12, and also the spec sheet at the bottom which lists components, frame materials, etc. on the individual models from '84-

edit: after looking at the specs on the Lemans 12 again, I notice the frame is not full chromoly. Tange 900 (a decent but lower level chromoly tubing) main tubes, high-ten stays. Again, I don't know about the Lemans RS, but the Lemans 12 appears to be more or less an entry level bike. For commuting this would make a fine bike, but in terms of dollar value it wouldn't be worth much-