How well provided is Paris Foreign Missions Society?

I'd like to know how well provided is Paris Foreign Missions Society. How come they have the largest private garden in all Paris and located in Rue de Bac (it was originally just outskirts of Paris when this seminary was founded), sending numerous priests into the far east Asian countries? Many of them were died and executed there, Korea included in the 19th century. Also, how did they provide money to the priests who took a nearly 10 month trip? Their building seems very elegant as well. I don't mean to criticize things, it just seems doubtable and marvellous to me, seeing their nature as missionary works and I respect their sacrifice. Or, do or did they get many donations to provide themselves, especially in the 19th century?