In Zen the kesa is not bought. It is sewn, and the sewing is practice.
The nyoho-e movement, associated in the modern period with Japanese teachers who returned to Dogen's instructions on the robe, holds that the garment should be made according to the dharma: cloth of no great value, dyed to a dull colour, cut into strips and pieced by hand. The sewing is done stitch by stitch, and with each stitch the sewer recites a formula taking refuge in the Buddha, so that a full kesa represents many thousand recitations. It takes months.
Lay practitioners receiving the precepts at jukai commonly sew a rakusu, a small bibbed version of the kesa hung at the chest, and it is given back to them at the ceremony with the teacher's calligraphy and their dharma name on the reverse. That object then accompanies the practitioner for life, and it is often worn at the end of it.
Before putting the robe on, the practitioner places it folded on the head and recites the Verse of the Kesa, which speaks of the robe of liberation, a formless field of merit, and undertakes to save all beings. The image of the field is literal in the construction: the panels and their borders reproduce the pattern of the rice paddies of Magadha, which the Vinaya tradition gives as the design Ananda proposed when asked for a pattern that could not be confused with lay clothing.
Dogen devoted a chapter of the Shobogenzo to the kesa and another to its transmission, arguing that the robe is not a symbol of the awakened state but its actual expression, which is why Zen speaks of receiving the robe rather than of wearing one.