Pretty simple tbh. I hit just about all the major buy/sell sites, Facebook, marketplaces, etc. to buy/sell/trade. Your standard buy low, sell high type of situation. Or, have relationships with the dealers and get watches and retail that sell for more.

Rolex for example is great if you can get it at retail or find a good deal but typically the margins aren't that great otherwise. Other brands have way better margins. Rare or hard to come by (but ones people would want) can bring in great returns.

It's a higher cost business to get into but have plenty of friends in the low to mid market that make some decent money. Less barrier to entry. You can do it with just about anything. Some friends are in collectibles, cards, shoes, etc.

Authentic only.