Liquidity

Liquidity is how quickly and reliably a watch can be sold at a fair price. A liquid reference has plenty of buyers and sells fast; an illiquid one may take months or need a discount.

Liquidity matters as much as price to a dealer, because the longer a watch sits, the more it costs to hold. Popular, well-known references usually trade on thinner margins precisely because they're easy to sell.

Factor liquidity into your offer: a slow-moving piece deserves a lower buy price than a fast one at the same expected sale price.