That's the earlier of the two versions of the A Zildjian & Cie Constantinople trademark. So 1973 to mid 1982ish on present evidence. If you follow the links in my signature you can get to my documentation of identification and years, as well as sales and weight data.

I suspect the comment that these are "so rare and popular, few musicians ever give them up" is just sales pitch not independent assessment of the situation. The A Zildjian & Cie Constantinople cymbals may be much less common than the A Zildjian cymbals from the 70s and 80s, but as we know from other "rare" models and lines that doesn't automatically lead to higher prices. Both the supply and demand side of the equation have to be there to create a higher price. Although there will be a few people who really seek out the A Zildjian & Cie Constantinople cymbals these seekers make up a very small proportion of the cymbal buying public so they don't have much impact on expected price.

The A Zildjian & Cie cymbals have a reputation for being relatively heavy which seems to keep prices down (at least for rides and crashes). They aren't all heavy, and when compared to the weights of Plain Jane A Zildjian cymbals of the same production era they don't really stand out in my weight stats. That's based on n=18 A Zildjian & Cie records in my database versus n=306 A Zildjian records for the same production era for all sizes and types of cymbal. Be warned that I have tended to focus on older cymbals so my sample sizes for the A Zildjian & Cie cymbals are low. But I try and do the best I can with limited data.

In the absence of specific data supporting a theory of higher prices, I tend to price them as A Zildjian cymbals of the same production era. For 70s 15" hats that means an expected median price of $200 with half selling for between $167 and $230 n=15. But there is lots of variability in prices which is why anecdotal evidence from one or two completed sales doesn't really capture the whole price distribution. The condition also matters to expected price. You should also get weights for them because that reduces some of the uncertainty in buyers minds.

Moving from independent evidence based analysis into the land of opinion about selling strategies, if you want to start with a price which isn't a complete giveaway price yet may also create interest I'd start at $230. I'm just starting to look at tradeoff analysis comparing days to sell versus asking price. It should come as no surprise that when somebody prices things at twice the going rate it can take a very long time to sell (if they ever sell at all).

Hope this helps.