Step 1: Student Deals
Check out: ultimatesteal.tk for more information.
Plus, your university may also have software available to you for a discounted price. Ask your IT department if this is the case and how they are obtainable. Often universities have a website which require your student number to login and provide you with software to download such as antivirus protection and course-specific applications.
Step 2: Online Sites
Another site is CraigsList. This site is very popular and suprisingly very useful. It is essentially a free online classifieds site. You can post anything (within reason) in any city for free. What's suprising is how fast you can get responses to your ads, sometimes within minutes of posting. This site can be useful to you if you are looking to sell something and you are in a rush or simply are having a tough time finding interested people. Plus, if you are looking to buy something and do not mind if it is second hand this site could be an excellent resource.
Kijijiis another site that is essentially the same as Craigslist but has a nicer layout.