You could be getting your psn codes free if you know where to look for them and if you are willing to put in the required effort to look for appropriate codes. There are several different types of codes that you could find online depending upon your individual requirements and upon the availability of the codes that you may have specific requirements for.
It is therefore vital that you first establish your requirements so that it becomes easier for you to look for relevant codes online. When you have a requirement for PSN codes for example, you will have to be specific when doing your searches online. This is because you do not want to end up getting codes that may not work at all with your gaming network.
What you could do to make your tasks even easier is get recommendations from your colleagues on where you could be getting these codes from. See http://www.stillnsync.com/free-psn-codes-psn-codes-generator-100-working/ for specific tips and advice.
They would be in a better position to direct you to specific websites where you could be getting your codes as expected and this would allow you to save plenty of time as well. If you would like to do your own search, then you could try looking on gaming forums as those places tend to be frequented by gamers who would be able to help you.