If you are familiar with WordPress and if you have basic experience running a WordPress website with no difficulties then you should be able to maintain a website like this.
If you have no experience at all working with WordPress:
I do not recommend to build the website on your own because you need a plenty of time and learning and it is quite likely that you will need somebody to help you out - pretty sure this would cost you more time and money than to hire somebody from the very beginning.
Basically WordPress and plugins and themes are built the way that you could build a website without coding knowledge on your very own.
But these learning management systems can do soooo much for you that I am pretty sure you will be lost without having any WordPress experience.
If you already have some WordPress experience and if you are able to install WordPress and themes and plugins and e.g. running a basic WordPress blog:
First, take a look at the documentation of theme you would like to have (you can find online documentations) - and this way you can decide if you understand the documentation or not.
If you do not understand what the documentation is about - hire somebody to do the job for you. It will save you time and money.
Purchasing a theme here on ThemeForest is a one time fee.
You gain six month of support (help) from the author - but always check and/or ask the author before purchasing.
You gain lifetime access to upates (as long as the theme is available on ThemeForest).
Do you know where to start?