I know that Michaels and HobbyLobby do not carry kolinsky brushes.
I am sure they carry Winsor & Newton paint, or at least they should, or at least they did last time I got oil paint few years ago. Winsor & Newton brushes I am not sure about... For the brushes, I only care that the brush is a real kolinsky, and don't pay attention to the brand very much.
If you are ok with OVERpaying for shipping,
Id order kolinsky brushes from:
GreenStuffWorld -
https://www.greenstuffworld.com/en/search?controller=search&s=brush
For the US, from the top of the dome, I use:
Blick -
https://www.dickblick.com/
Utrecht -
https://www.utrechtart.com/
Check them out. Hope this helps.