Magnesium tablets are cheap and easily available. You can even try alfalfa, seaweed tablets and do it that way. It needs other factors with it to be absorbed, though. Try Magnesium mixed with calcium and Vit D, a sure absorption formula. BEST is to use raw juices, have a juicer at work, carry bags of carrots, celery, parsley, a small slice of beet to work and juice something right in the office.
Juicers are easy to clean.
Too much fuss is made about cleaning a damn juicer. You lift out the ring of crudded vegies, slop it in a wastebasket, rinse all metal parts in the sink and leave upside down to air dry.