Dyson sells them on their website for the newer models, and you can always call their customer service to see if they have any for the older models.

This goes for lots of parts for lots of manufacturers. I needed a part for my Vitamix that wasn’t available anywhere online. I called Vitamix and not only did they have it, they sent it to me for free.

Always try the manufacturer even if their website doesn’t offer what you’re looking for. It never hurts to ask.