The cost of permanent exclusion from school is an issue that has been gaining increasing attention in recent years. However, efforts to estimate these costs have mainly focused on those incurred after the student has been excluded, such as those for alternative education providers. Less focus has been given to costs associated with processes leading up to exclusion, including the time spent by school staff and other professionals (e.g. counsellors, special education needs specialists) in efforts to prevent exclusion, or to mitigate negative outcomes. Moreover, the unpaid time and effort spent by parents/carers during this process often go unaccounted for, despite significant financial implications from foregone productivity and income. In this paper, we use a series of five case studies based on in-depth interviews with different stakeholders from England, Scotland and Wales to illustrate the potential involvement of the professionals and parents/carers in the process leading up to -- or the measures preventing -- permanent exclusion, and estimate the associated costs. It is important to highlight these costs for future resource planning, as well as to present a more comprehensive picture of the true costs of permanent exclusion.