There is a similar question just a few days ago about Rolex.
Paying full retail and then trading in to 2nd hand watch shops is never a good idea if you intend to get back a large part of your money.
I disagree that the resale value of Maurice Lacroix is bad. All brands are like that except the few hot watches in Rolex and Patek's catalog. Or some special Snoopy Omegas. Many moons ago when I was younger, I asked a shop which i am buying a watch from to quote me a figure for my Tag. The number that was given to me nearly gave me a heart attack.
ANother observation is in terms of percentage, watches that are lower priced ( <10k ) will be hit even more because watch shops typically have a minimum profit number before they are willing to take it in.
If you don't need the money urgently, willing to ignore scammers/be smart about safety, private sale is the key.
The same goes for cars. A used car dealer once quoted me a number than is RM25k lower than the market value of the car. He needs to pay his staff, rent, family, tax etc and I can understand that.