Automated Vehicle (AV) services hold significant potential for revolutionizing public transportation networks across Europe, promising to elevate public service quality and enable more sustainable, citizen-centric mobility. However, to successfully integrate these innovative mobility options, it is crucial to understand their economic impacts on public transport systems. This study aims to provide a comprehensive cost analysis of AV mobility services, particularly automated minibuses, through a scenario-based approach using a developed Fleet and Cost Calculator. Employing a sequential exploratory research design, we collected qualitative and quantitative data to clarify the pivotal criteria influencing AV service costs. As part of the Horizon ULTIMO Project, we calculated and analysed AV service costs within the Oslo-Groruddalen (Norway) demonstration site across two different mobility scenarios. The analysis not only highlights the economic feasibility of integrating AVs but also provides recommendations for the use of automated mobility services, focusing on cost efficiency. In terms of economic feasibility, the analysis showed that AV service costs can decrease between 2,5% and 56% by adapting certain operational factors, such as vehicle supervision, energy costs, and maintenance costs.