As far as I am aware, all of the big brothers were made in Hong Kong. However, there are variations with and without the 'pat pend' under one hoof, which also have some minor differences in their colouring. Depending on whose looking, a non pat pend Salty could fetch a couple extra $ compared to the pat pend version. I think at least $12 for regular pat pend Salty.
I'm afraid I have no idea on the Sweetheart Sisters.