At a Detroit research program from 2004 to 2005, out-of-treatment chronic daily heroin users (N = 100) were interviewed to evaluate relationships between past 30-day income and factors influencing heroin price, expenditures, and consumption. Weekly heroin purchasing frequency was positively related to income and number of suppliers, and negatively related to time cost (min) from primary supplier. Daily heroin consumption was positively related to income and injection heroin use, and negatively related to unit cost of heroin. Implications and limitations are noted. Simulations are underway to assess within-subject changes in drug demand.