It is always better to try assembling your own system with the features that fits the bill. While all branded ranges and levels of desktop systems where available with the flexible finance options, assembling the system not only involves cost reduction but it makes you well aware of what you have within your cabin box.
The knowledge about your system's configuration is vital in order to be the original master of your desktop. Otherwise, every time you have to long for the help from some engineer who is either a professional or experienced in the field of system assembling.