Look for discounts on online shops
Most of online stores like Amazon, Apple Stores and so on have a box to enter promotion or discount codes. Usually they are little discounts or free shipping, but sometimes you can get a truly bargain.
There are some webs that mantains an updated databases on these codes, so I really recommend to waste 5 minutes looking these websites for the code you need:
www.currentcodes.com
www.retailmenot.com
www.couponmountain.com
www.searchalldeals.com