They can, but it will be very expensive most of the time as they will be using OEM and at retail price. You might have better luck at mom and pop vacuum shops if it is a common vacuum (try several, the guys that hoard vacuums and parts have the best odds).
You can look online and find a motor yourself and have the shop install it for you too.
But it is very very rarely a motor can not be rebuilt. So always try rebuilding first.
Miele is tricky because they are imports and most of their userbase is in England and Germany. I have a rare Miele myself and pretty much everything I need for it would have to be shipped over from England, Germany, Netherlands. I haven't even looked at the motor yet, the previous owner trashed it as a garage vacuum and it's a big mess.