that's the wrong question - the value is in the eyes of the beholder. the company doesn't exist anymore, so the only reference point is the market of vintage razors, e.g. ebay, the classifieds...
you've seen the current prices on ebay, as far as i can tell they have been steadily going up.
you'll probably get a better deal here, not guaranteed of course, but the price is decided between you and the seller, while on ebay is between the top two bidders.
the question is how badly do you want one of them?
7/8 is a fairly rare size. just find what the current production 7/8 razors cost as a reference. depending what you value (shaveability, collectabillity, cosmetics) it will be either an excellent deal or may be an ok purchase.
yeah they are branded by the same company - a barber supply vendor who didn't make razors themselves, just put their labels on stuff they contracted out.