Hi Letty, you can use almost any low shank darning foot. The one that came with the 222 is part # 171071, but it's pricy when you find it.
Sew-Classic sells these ones:
http://shop.sew-classic.com/Low-Shan...D-SCF60410.htm - This one is my least favorite, but everyone has different likes.
http://shop.sew-classic.com/Low-Shan...foot-55417.htm - This is the most common one that I see when I get a machine that has a darning foot. I've also seen ones that are all metal, but the same style otherwise. I would personally take the full metal first.
http://shop.sew-classic.com/Low-Shan...-SCF4021-L.htm - This is my personal choice of feet to use, out of the ones that I have here.
http://shop.sew-classic.com/Low-Shan...td-SCF4021.htm - This is the one that Leah Day sells and "raves" about, after you make the modifications -
http://freemotionquilting.blogspot.c...your-foot.html - I have this foot here, but haven't taken the time to make the modifications yet, and haven't used it as is, so I have no real opinion on it.
Here's another post about the modification, pics instead of video:
http://freemotionquilting.blogspot.c...tbreak-it.html