Government funded assistive technology (AT) supply schemes in Australia operate at less than optimal levels. Not only are they failing to make best use of limited resources, they are also contributing to detrimental outcomes for AT users. Detriments are caused either by delaying the supply of the devices, or making available only those items fitting within a budget rather than the needs of the AT user. Costing the additional effects of delayed supply or inappropriate supply of AT is necessarily complex and existing economic analysis techniques are not suited to do this. Such costs can be extra or extended hospital stays, additional medication for pain management, lost opportunities for employment and contributions to society, or physical and emotional stress for family carers. The need to take a more holistic approach is therefore evident. To this end we have developed a novel way of using the International Classification of Functioning, Disability and Health (ICF) to document an AT user's current situation and to compare it with a situation the AT user considers optimal. We draw on system-focused stress-testing techniques used in financial systems management to analyze the costs in both situations. The main content of the paper discusses the methodological issues arising from analyzing complex systems in this way, while first results are presented in a separate paper by Bringolf and Schraner in this volume under the title ‘The Economics of One Person's AT System: First Findings’. Here we detail how combining the framework of the ICF with scenario analysis allows us to research the economics of AT. The ICF provides a framework to capture the AT user's perspective of their current situation and their desired optimal situation. The financial systems management techniques can then analyze not only the relevant costs in both situations, but also to include the less visible costs, which often appear only at a later point in time. We conclude that this methodology, whilst still being trialed, provides a useful way of examining complex economic situations. We have one proviso, namely that providing optimal solutions for any individual depends largely on the AT user's level of knowledge about available AT devices, about access to care work, and about ways to enforce the rights to accessible environments and to realize their civil rights. This level of knowledge and the information systems that can increase it may prove to be the next main challenge in providing optimal AT systems to individual users.