I often recommend that people buying new PCs should consider refurbished. In my experience, used is typically better than new. I want to say always, because I’ve never had a bad refurb.
Refurbished is a computer sold secondhand by the original seller, which could be the manufacturer or a retailer. Hypothetical: Jack Consumer buys a new Mac from Apple, but after getting the computer home he sees the new Dell TV commercial with Sheryl Crow. He returns the Mac and buys a Dell. Apple still has to sell that computer, but now potentially at a loss and discounted to future buyers. Maybe Jack liked his Mac but it had a bum hard drive, so he exchanges it for another. Apple still has to sell that computer, albeit with the hard drive replaced, again discounted.