Are you sure you don't just want to do it yourself, and ask us for assistance/guidance? I'm asking this because unless you plan on paying someone to maintain your new site after it is built, you will have to know how Shopify and your apps work. It's really not that difficult to setup a Shopify site. I know a lot of teens and preteens who have done it.
But if you have the moolah and you just wish to focus more on your product than the tech, then maybe paying someone is better for you. Just make sure that you try to learn a little about what's going on with the back-end of your website so if something suddenly goes wrong, you will have an idea on what might be broken (so you don't get taken advantage of by whomever you hire, not saying that will happen...but you never know).
Tomas