How To Start a Dispensary in Colorado It is quite easy to open a medical marijuana dispensary in Colorado under amendment 20. As long as you have money to start it, have the ideal location and selling products or services that is in demand, you are good to go. in Public bookmarkswith amendment_20colorado_dispensarycolorado_medical_marijuana Note: It is quite easy to open a medical marijuana dispensary in Colorado under amendment 20. As long as you have money to start it, have the ideal location and selling products or services that is in demand, you are good to go.