I will setup a basic Team Site for you, also during the rest of the day, I will explain each setting of the site, I will provide you advices about how to handle site growth (subsites, list, libraries, users, permissions, etc.), the features you can add, how to install and use Apps, how to edit pages and add improvements with JavaScript. In other words I will share with you all the best practices that we can review during that day, you can choose the priority of the topics you want to review, your choices and the time you want to invest to each topic will dictate the reach of the session due to the one day limit.
As you may guessed, I'm offering to guiding you in the process of building your SharePoint Site instead of building all for you. I suggesting this because I think this may work well for you due the description you provide and the money you expect to spend on this. Of course I'm open to do a well documented architecture design and perform all the setup, however this activities cannot be estimated without knowing your requirement details, at this point there's only an abstract description of your requirement and its hard to guess the size of it, it will be better if we have a conversation about your requirement so I can provide you a accurate proposal.
Regarding my experience, I'm a fully specialized SharePoint Consultant and I have been highly focused on SharePoint Online (O365) in the last couple years, but I started working with SP Online more than 3 years ago.