A purchase solution approach is one that involves acquiring a COTS software package from an external vendor or provider, rather than developing a custom solution in-house. A purchase solution approach can offer several benefits, such as faster delivery, lower cost, higher quality, and reduced risk. However, a purchase solution approach also has some drawbacks, such as limited customization, dependency on the vendor, compatibility issues, and licensing fees. A BA should evaluate the pros and cons of a purchase solution approach against the business needs and requirements, and compare it with other possible solution approaches, such as outsource, exploit, or create. References:

Evaluating Candidate COTS Packages, ArgonDigital

Seven Insights: Agile and Custom Off The Shelf (COTS) packaged software, Kenny & Company

COTS Software Procurement Methodology, IGI Global