I buy mine from Sayila (Netherlands; free shipping for orders over 20€), but they are not swarovski if you are specific about that. They mostly sell chaton montees rather than rose montee (as in the pic), but some roses too. I prefter chatons as they have much more sparkle in them.
Good luck with your search!
edited to add: for some sizes Sayila sells settings for both flatback and pointed back swarovskis, but that will require some extra fiddly work to fold the prongs so the stone sits tight. An option if you can't find already mounted crystals.