Which breyer models are extremly rare?

Extremely rare Breyer models include the "Ballet Horse," produced in 1959, and the "Old Timer," released in 1970. Other notable rarities are the "Hollyhock" and the "Giraffe," both of which had limited production runs. Additionally, special editions and models from the 1960s and 1970s, such as the "Bobby" and "Darla," can also command high prices among collectors due to their scarcity.