So you want to build strength in your legs and lower body in general? Using a glutes machine is not a bad idea. The Maximus100 Glutes Workout Equipment can help. It is a 14″ base for most dumbbells (16″ also available) and holds up to 100 lbs of weight. It helps you perform free weight exercises and push your body harder.
The Quadruped Hip Extension exercise focuses on the gluteus/butt muscles but does not require you load your spine with weights, as with squats. Sets you back $69 + s/h.