How much did a horse cost during the Middle Ages?

The price of a horse, according to a Medieval Sourcebook (link below) was 10 to 20 shillings for a draft hourse, but could go to twenty times that, or more, for a fine riding horse or a war horse. At that time, a laborer would earn about forty shillings per year, according to the same source. The source shows a lot of variation in prices, so should not be taken as absolute.