A new study of technology-driven companies that offer to purchase homes directly from consumers—also known as iBuyers—attempts to show the true costs of this business model to sellers.

Real estate analytics firm Collateral Analytics examined about 6,000 transactions across four markets—Phoenix, Atlanta, Charlotte, and Las Vegas—to determine how much iBuyers were paying for properties compared to market value while controlling for factors such as size, age, and other variables. The median discount—how far below estimated market value purchase prices were—was between 4.5% and 6.9% for one major iBuyer and between 2% and 3.3% for another.

The direct costs (often in the form of fees) of working with an iBuyer can run from 7% to 10% of the offered price not including credits for requested repairs, according to Collateral Analytics. When those costs are combined with the discounted purchase price, the total cost of working with an iBuyer can be between 13% to 15% depending on the firm, according to Collateral Analytics.