I'm not very knowledgeable about bikes (yet). I'm searching for a decent road bike but do not want to pay a fortune. I found this Cannondale "R30"? (which I haven't been able to find any info on) series bike at a pawn shop. It's got Shimano Dura Ace everything as far as I can tell. How can I find out how much it's worth? They're asking ~$350.
Seat-of-the-pants "analysis": Dura Ace is Shimano's top-of-the-line. Off the top of my head, I see bikes with components two "notches" lower (Shimano 105) for $500-750 or more. A LOT depends on age (vintage/technology) and condition of the frame, components, etc. Cannondales are aluminum; have the frame checked carefully for cracks. If it's in reasonably good shape, it's a tremendously good deal. Even if the frame is cracked, a good Dura Ace gruppo is worth at least that.