If you are in the business of regularly shipping products, or indeed, your company regularly stores a large volume of goods, then you should certainly consider investing in shipping containers. Storage containers of this kind make for a great investment because, not only are they able to ship and store large volumes with ease, but they are built to last a long time and they are affordable.
A lot of companies who use shipping containers tend to rent their 20 or 40 foot cargo container by the month, or perhaps on a longer term contract, but unless they are planning to use the container for only a short amount of time, it would be more prudent of them to buy it outright.
The cost of buying even a 20 foot cargo container may seem expensive, but it is certainly a good investment, especially if it is to get a lot of use.
The main reason why it pays to buy a shipping container is that they are very valuable on the resale market, so if you are going to use them on a regular basis, you may as well pay out to buy one because you will be able to recoup some of your costs by selling the container for reuse later. If you simply hire a container then you will not be able to recoup the money. You may even be able to find a second purpose for your cargo container yourself at some point.
Of course, if you are only going to need a shipping container for a week, a month or even a few months, it may well work out better to simply hire a container. This is a judgement you must make depending on your circumstances, but buying should not be immediately ruled out.