I have a ball winder and a swift. I really didn't think I needed either. I got the winder first from JoAnn's and was disappointed because the arm wouldn't stay locked in position and I should have sent it back right then but hate doing that and did get it 50% off. One yr. later-----I took the thing apart, tweaked it and seems to stay in the lock position better.
The swift , I added this right after Xmas and love. But, check prices before buying--I bought mine at a LYS for around $65. Now I see them a lot of places a lot less expensive--say around $35.
So the moral to this story--shop before you buy!!