Yes, business size matters when determining customer acquisition cost. Businesses with many employees will spend more to gain customers, since the salaries of their marketing teams (and any other employees in the sales cycle) are an important factor in their CACs, while a business with few employees will spend less. However, large businesses with high marketing costs typically gain more customers from their campaigns, meaning that their customer acquisition costs are usually spread across a larger number of new customers. This ultimately keeps their CAC within a reasonable range.