Cheap tip number 28 million or something: instead of buying a new computer, build it yourself! Gizmodo links to the article on Lifehacker titled The First Timer's Guide to Building a Computer From Scratch. The article also offers a better reason than saving money for building your own computer: "building your own PC makes you feel like a badass."
About 11 years ago I built my own computer. The hardest part was choosing the components (and of course, back then there was a lot less to choose from). Everyone else thought I was a rockstar and I was like you know, most of the time there's only one place a thing can go. And my local computer parts store was owned by Brad Pitt's brother--LOL.