Soooo... Ratings is a tough one because it not only matters what breed, but also what sex, and even can matter what colour. Something that the breed doesn't have much of will sell a LOT better than something the breed is oversaturated in.
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Bravery really depends on the other ratings. And WHO you're selling it to. It may only have value to a specific individual while others shrug.
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Uninheritable patterns will come down to the individual buying, too. Really, they do not add any breeding value to a WC horse, it's just for show. So, many people won't go out of their way for a brindle or chimera high rating. You've gotta find the right person.
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Gauging value is best done searching for other horses around that rating. I say rating and not colour because if you search that specific coat and wind up empty-handed, you're still back to questioning price.