We have the cordless oster clippers.... they are quiet and cordless, which the with out cord is the best.... our horse accepts everything except the ears being clipped.... I highly reccomend cordless but other than that, I don't really know. Ours were around $300.
"Equine-facilitated therapy employs a form of biofeedback for practicing self-awareness, emotional management, and relationship skills that human role-playing exercises and discussion groups cannot begin to access." Linda Kohanov (The Tao of Equus)