Nice bike, and as suggested, you will get a lot more responce from the C&V forum. I'd say it is late 60s, the rear derailleur should have the year stamped on it. $500 is a fair deal. Although you may score some really good $$$ with the fenders. Those were typically removed and thown away back in the day and I would guess they would go for $100-$200 on ebay (if they are branded Frejus). The Italia saddle is also somewhat rare here in the US.