Back in 1973 when I bought my first good road bike, a Raleigh Professional, the Record side pull brakes sold for about $150 per set. No idea how much a full group would have cost. Keep in mind that back then a full group also included a pair of hubs and pedals. I would say that in today's dollars a full 1973 Campagnolo group like the one that came on my Professional would be more expensive than today's equivalent. Even after many years of use, all the components from that groupset are still in good working order