Ingestion will not be as efficient, it always uses more, thee best method described here is buffulosoulja's where you vap it, then make cannabutter out of the scat. The cannabutter is still VERY potent, but a good vaporizer is going to run between $300 and $600 USD. If your friend is looking at those three options as a legitimate medical patient, then he/she should consult their doctor as to the best method and dosage for them, as anectdotal evidence on a forum is not a true perscription. One ounce, in a vaporizer smoked three times daily would last about three to four weeks. However, fdd is right about dosage....a medical user will have to smoke more than three times a day once they have built up a moderate tolerance (and depending on their illness).