In my market, $50 would be full value for the bike as it sits. I had the updated version of that bike (Sport 12) that I donated to the co-op.
I paid $10 for mine about a month ago. It had a front basket that a friend wanted. The rest went to the co-op. Note, the one I had needed to be rehabbed. I would have been upside down and not even able to cover the cost of basic consumables.