Hi! Welcome to Hamster Central!
It's great that you are doing a bit of extra research before getting another hamster
. The Northern Hamster Club has a list of breeders so it would be worth contacting the secretary to find out about local breeders for you.
Both Winter Whites and Syrians are excellent pets. My Winter White is from a breeder and he is the sweetest thing ever. I can't compare to pet shop hams, since I've only had one hamster.
The Maxi Duna Multy would make an excellent cage for any species of hamster so you can be quite flexible there. A Winter White would be able to make the most out of the space though (smaller stuff needed than a Syrian) but it is still a great cage for a Syrian.
Good luck with your future hamster
!