How Much will ACO Creation Cost?

It seems that CMS and the AHA have quite disparate numbers:

The American Hospital Association (AHA) released an estimate of costs for establishing an accountable care organization (ACO) per Section of 3022 of the Affordable Care Act (ACA). In its 429-page guidance issued April 30, Centers for Medicare and Medicaid Services (CMS) estimated start-up costs and one-year operating costs at $1.755 million. The AHA analysis said costs would range between $11.6 million and $26.1 million.