If you look at the title of this thread it mentions "for a workshop". To make a decent workshop you need a concrete floor. Then you need walls to put insulation in, and a ceiling with insulation. Then you need to run electrical power to the building and depending on where you are located, you will need heat or air-conditioning, or perhaps you will need both.
The structure pictured has no walls, just posts to support the metal roof. To make a workshop, walls will have to be built and if you build walls you may as well have the walls support the roof. For all practical purposes the only thing you are getting with this structure is the roof. Problem is, applying insulation to the metal roof will most likely mean using spray foam, which, while a very good insulation, it is not exactly the cheapest thing to have done. With what it costs to purchase the structure you could probably build a conventional roof, or at least come pretty close to the cost of building it.
If all you want to do is have a place to store stuff, and if you don't mind having a dirt floor, you can maybe put up some sort of walls just to keep the wind and the weather out. I could see doing that, it would allow you to at least keep your stuff under some cover. But to make the structure into a really nice workshop, I would say that is not a very economically viable option.
That's my opinion, others may think differently, but that is the way I look at it.