Hello! It seems that if it's challenging to set a price for a "comprehensive product" related to advertising setup, you could focus on pricing the individual components of that product in your specific case.
For instance, the components might include target setting, writing or editing text, design or tweaking of layouts, developing a sales funnel, creating chatbots, creating a content plan, and so on. You can check what freelancers or other agencies typically charge for each of these elements and use that as a baseline for your pricing.
By the way, since your primary focus is SEO, you could offer advertising as an additional service at a price below market value. This strategy might help you attract even more clients to your primary service.
Also, another point to consider: You mentioned that this work "doesn't really cost me anything," but remember, you're spending your time. Time that you could otherwise allocate to tasks that yield a particular monetary return. As an option, you can divide your typical monthly income by the number of working hours to determine your personal hourly value. This will give you a better understanding of what your time is worth.
