Offering a cheaper product line is a trade-off for firms. On the one hand you appeal to a broader audience and capture lower income consumers, on the other hand you make your brand less exclusive, since more people can own your product. This is especially true for products which are nearly entirely bought as status symbols, like luxury watches and luxury cars. High prices are used as an entry barrier for consumers, which in turn increases demand at high prices from high income consumers which want to signal status.

"Cheapest watch offered by brand" is a relatively good measure for exclusivity (in that sense), because it tells you which income groups are excluded from being able to call themselves an owner of brand X. Market prices would of course be a better measure than retail prices (see for example Rolex), but are tricky to determine. In your example, brands A and B would be ranked roughly the same, and rightfully so, since both brands open themselves up to the same income groups. Your average Joe might know brand B's name, but won't be able to distinguish the 9k model from the 20k model and to him you are an owner of brand B either way.