How can I duplicate this site/get a theme similar to this site?

Context

So I was taking a look at this site https://highschooltutors.com.au or https://learnmate.com.au. They have features which are similar to that of Freelancer, in that you can post your own ads, but it centres more around an educational system, rather than, say, products for sale.

Question

How would I go about building a site like this on WordPress? Is it feasible to take and edit a free ecommerce templates or would I be better off buying a theme for a freelance marketplace and trying to adapt that? How much would it cost to hire someone to make a site like this?