The supply of and market demand for assistive products (APs) are complex and influenced by diverse stakeholders. The methods used to collect AP population-level market data are similarly varied. In this paper, we review current population-level AP supply and demand estimation methods for five priority APs and provide recommendations for improving national and global AP market evaluation. Abstracts resulting from a systematic search were double-screened. Extracted data include WHO world region, publication year, age-groups, AP domain(s), study method, and individual assessment approach. 497 records were identified. Vision-related APs comprised 65% (n = 321 studies) of the body of literature; hearing (n = 59), mobility (n = 24), cognitive (n = 2), and studies measuring multiple domains (n = 92) were proportionately underrepresented. To assess individual AP need, 4 unique approaches were identified among 392 abstracts; 45% (n = 177) used self-report and 84% (n = 334) used clinical evaluation. Study methods were categorized among 431 abstracts; Cross-sectional studies (n = 312, 72%) and secondary analyses of cross-sectional data (n = 61, 14%) were most common. Case studies illustrating all methods are provided. Employing approaches and methods in the contexts where they are most well-suited to generate standardized AP indicators will be critical to further develop comparable population-level research informing supply and demand, ultimately expanding sustainable access to APs.