Also, you CAN get it serviced from any random store that claims to work on Rolex, it is just that if they have to actually send it to Rolex, Rolex won't work on it.
Exactly that is because Rolex is all about lousiness in customer service and all they care about is ripping you off on a lousy, overpriced watch made by robots in the quantity of nearly one million a year. If your Rolex goes bust in 20 years time, they can't repair it for you because they have an explicit policy of keeping the parts for only 20 years. For other brands such as IWC and Patek, they will actually keep the blueprints and make a replacement part for you if that is necessary in 100 years time. Moreover they will service your watch even if it is from the grey market (even Cartier does that!) because they actually care about every single watch that went out of their workshop rather than Rolex factory. In any case, warranty is only two years so after two years, you will be paying for the service cost anyway whether you buy it from an authorised dealer or not.
Coming back to the question that the lady who started the thread asks, if it is a quartz Constellation , buy from a non-authorised dealer if that gets you the best price. If it is a mechanical Constellation, also buy from the non-authorised dealer if that gets you the best price. The reason is because:
1) For quartz, it is easily serviced and a gentleman in your local market can easily sort out quartz problems; I have no intention to get my quartz Patek Twenty~4 serviced by Patek itself because that will cost me 525 Swiss Francs.
2) For mechanical, it can also be easily sort out by the same gentleman in your local market because the movement inside is ETA 2892-2 (95% sure of the number but I don't remember off by heart
) which everyone knows about and it is not like a Grand Complication that requires expertise!