Buy barebones,build,or get a prebuilt?

I am in Canada and the price difference from Canadian pricing compared to USA pricing is rather significant, with the USA being cheaper. I have the skills to build a system from scratch. I am just a cheap and frugal guy that is looking for the best deal. So what would you recommend? I am looking for a gaming rig that will not be out of date in 3 weeks. My budget will be as close to $1200.00 as I can possibly get. Any ideas? Any expeirence? Any hints?