If I were to go out and purchase some equipment, I would go for a full dumbbell set, one barbell and squat rack. Stability Balls, and a door jam pull up bar.
Ditto on the dumbbells and squat rack. I like the idea of the multi-weight dumbbells that you can dial in various weights from 5 to 55lbs but couldn't tell you if they are worth the money. It would be nice to avoid a rack of dumbbells sitting around.
I own a Nautilus Smith machine I got at Costco that I highly recommend but it is pretty bulky. Still it's great when I can't build the enthusiasm to hit the gym.