Six Head Rocks (black with logo) in a heavy duty, waterproof drawstring bag. This is a station-in-a-bag! Stations are a great way to structure the individual skills portion of your practice. The only downsides are that it requires coaches at each station and lots of space. The Head Rock takes care of both of these issues. Have a warmup station just before the shooting station. This prevents a long line of players waiting to shoot. How about a Defense station of Ms, Ws and 8s?
Are you constrained in the winter by limited indoor space? You can have players work on a number of exercises in a small space without chasing balls (or rolling an ankle on one). Remember, the Head Rock is heavier than a ball. It is a real workout when you go for 60-90 seconds!