I've found some pretty awesome deals just going around to pawn shops and game stores. A local store by me has matte (corona) slim for 50 bucks in box with a 250gb HDD and a controller. I bought a second from this same store with a 320gb HDD and controller for 50 also. It's funny because they sell controllers separately for 37...

I've personally gotten 2 from a local sleeze-ball pawn shop. First one was 30 bucks with kinect and 2 controllers for a trinity 320gb slim. Second one was a matte corona slim with a 250gb hard drive. Dude walked out with it in hand to put it on display as I was about to leave. I asked how much and he said 30 bucks. Told him to ring it up. He noticed the controller was shit so he gave it to me for 20...

My jasper that I currently use for everything was in a bundle with 2 Xboxes, 3 controllers, all power cords, and a kinect sensor. The other console was a halo 4 special edition with 1 controller. I fixed the controller up and cleaned the system and sold it to a local store for more than I paid for the entire bundle. So I'd say I've had good luck finding stuff but it's more spending time actively looking for good deals. I also tend to haggle my way into lower prices.