kitsandparts.com - not an advertisment

  I just want you to be aware of them because they are super-handy and have low prices on parts which cost more anywhere else.

 I have purchased toroids and snap on ferrites from them and had my stuff arrive quickly and well-packed. That was some time ago.

I have not bought any kits, or even other parts from them, for what it's worth. They seem like a good source to know about and I am in the process of ordering more toroids from them right this minute.*

 What I'm buying are large toroids made of a low-frequency-optimized mix, the FT140-77 from Fair-Rite.
PS: their store is simple, easy to use, and oh so clunky.

* (as I experiment with common mode + PI filters and other means to mitigate the camera noise issue with the 3D printers)