This was my first thought but then again I don't know how expensive the one was and if they built one and it launched successfully, what would they do with the second one? Seems like a damned-if-you-do-and-damned-if-you-don't scenarios.
Although whether it would cost an additional $200 million to build a second is another question, but I doubt there would be that significant an economy of scale for just one extra unit.
I think a lot of it is using electronics that are less susceptible to radiation along with needing a clean room to actually build the thing. Not sure if that accounts for the entire $200 million.
