I just sold a white '75 UO8, like yours. After a thorough cleaning and a tuneup with new cables, chain, and bar tape, all I could get for it was $100. There's a lot of them out there, so the value really is what it's worth to you, not what you could sell it for. They're good basic bikes and ride well. For $140, it would have to have almost flawless paint and all its original components for me to say it was worth it.