This paper describes the systematic development of a low-cost robotic mobility platform tailored for assistive tasks, specifically addressing the critical mobility needs of two vulnerable user groups: visually impaired individuals and the elderly. To lay a solid foundation for the design, this work first conducts an in-depth analysis of the prevalent challenges plaguing existing assistive mobility devices, such as prohibitive manufacturing costs that limit accessibility and functional fragmentation that fails to meet diverse daily needs. Corresponding core design criteria are then derived from the specific requirements of the target users, including robust terrain adaptability for complex indoor and outdoor environments and a strict cost ceiling of under €500. In response to these demands, a hybrid wheeled-legged locomotion structure is proposed, featuring a five-wheeled base integrated with adjustable front legs; the conceptual mechanical design of this structure is described to illustrate how it enables seamless transition between efficient flat-ground operation and reliable stair-climbing capability. For prototype fabrication, cost-effective commercial components are prioritized, including an Arduino Nano microcontroller as the control core and MG996R servos for actuation. Comprehensive assembly and performance testing are carried out to validate the platform’s efficacy. The experimental results demonstrate that the fabricated prototype weighs merely 1.9 kg with a total cost of approximately €400, and it achieves stable navigation on typical urban surfaces such as asphalt and interlock paving, as well as safe stair climbing—all performance metrics are fully aligned with the predefined design specifications, verifying the feasibility and practical value of this proposed low-cost assistive mobility solution.