a typical online store
ebay, aliexpress and so on
- it is absolutely different things, at least on the count of templates, and as well as on the count of ui elements, etc.
You ask the price, but how to form it on such a meager description? Only admin can have the scattering to 1000% of the cost, depending on the engine.
Plus the price depends on the technology stack. Do you use a framework the type of bootstrap, how much will the js scripts, dynamic elements (sliders, radio buttons, animation)
All these questions have to ask yourself a web designer with 2 years experience. Or are You just under the wp two years to typeset?