Use: Graphics have a variety of uses. With graphics software there is a huge list of things that can be done. You can design logos, e-covers, headers, webpage graphics etc. They may be used online or offline- that is, in web pages across websites or in print in the form of manuals, documents etc. Some use graphics software for professional purposes like engineering, architecture, arts etc. While deciding graphics software, determining the purpose is important.
Skills: The skill of the person is the next category. If you have no skill in graphics design then you only need a professional design software which is easy to use and handle. However, if you are a professional graphics artist then Photoshop is the best graphics software for your purpose. Before you choose the cheapest brand in this case, you only need to know the specifications and varieties available in the market. To know the best cheap brands you can post your questions in graphics forum. If you have all the basic skills then you can manipulate and study easily so that you can get what you want. If you know exactly what you need then you can easily zero on the right graphics software for yourself.
Compatibility: This is a major factor. Any graphics software that you choose must be compatible with your system and meet all its requirements. This is more so because there are some graphics software that need a high speed operating system. Otherwise, it may take ages to come up with a good, meaningful design.
Once the above facts are decided, you can acquire cheap graphics software easily. There is a wide range of graphics software programs available for everyone- from layman to professionals. You just have to choose the right one according to your needs.