Nancy's Notions sells a lot of the machine feet. I have never bought any but they have them all on one page so you can see the difference. I clipped the page and put it inside my machine manual so I could easily identify which one I needed. It is a good reference page.

As I stitch all my quilt bindings on, I bought the SID attachment for my Janome and I love it! I also have the blind hemming foot and it is different than the SID one. Use whatever works for you, but don't try other brands with your Janome. I have other machines and tried theirs on my Janome and they just don't work well.