I've seen these before. I'm not sure if Rossin built these or were the just a middle man between Guvin and some larger Iltalian contract manufacturer. Early to mid-1980s. Lower grade Campagnolo derailleurs and everything else 2nd tier Italian. The other ones I've seen had nice but not great workmanship and quite a few concessions. Definitely mid-range and I'd place them at the lower end of that range

As for value this ones is very dirty around the bearing movements, so race condition may not be good. You're not in what I think would be a in hot market and winter is coming. My offer would be $100 CDN. Even with new consumables, in season, I'm only seeing $200-$250 CDN.