So you may ask yourself, how can I buy for cheap and sell for more a year later? Here is how. Buy cheap. Refurb or online. Save tax and shipping. Thats the beginning. Then you add hard drives and ram on the cheap. I look for deals at hardforum and I fill the system up. Might cost me a few hundred. Now when people see my system on ebay they go to apple and configure it and it comes out to thousands more than I am asking because apple charges out the butt for ram and hard drives. Makes my system look more appealing, and it is. Just throw in some hard drives and ram and it will sell form more than you paid for all. Easy.
Its not a scam. Anyone can find the hard drive and ram deals on their own, but most shops don't want the hassle.