Purpose

This paper aims to explore how small and medium-sized enterprise (SME) purchasing is shaped through supplier–buyer relationships to extend product lifetimes.

Design/methodology/approach

A qualitative single case study design is adopted, involving a workwear manufacturer, a service-oriented distributor and four SME customers in Sweden. Drawing on the industrial network approach (INA), the study examines how structured decentralised purchasing models evolve through high-involvement supplier relationships.

Findings

The findings demonstrate that high-involvement supplier relationships enable SMEs to overcome internal resource constraints by leveraging internal and external capabilities. Structured decentralised purchasing models, coordinated by a service provider, balance operational efficiency with user safety and satisfaction and contribute to extended product lifetimes. The study highlights the underexplored role of users in sustainable purchasing.

Practical implications

The study provides guidance for both SMEs and suppliers seeking to balance operational efficiency with sustainability. It emphasises the value of service-oriented intermediaries in facilitating high-involvement relationships that improve SME purchasing and product lifetimes.

Originality/value

This paper advances sustainable purchasing literature by applying the INA in the context of SMEs. It provides a novel understanding of how supplier interactions, particularly those involving users, can support structured decentralised purchasing models and extended product lifetimes, contributing to improved outcomes with regard to sustainability.