Hello,
SAM does not have an explicit model for turbine cost for offshore turbines, so yes, the same cost is applied regardless of technology specifications like hub height. The cost that is applied is simply the average cost of an offshore wind turbine based on a 2015 report.
For the offshore balance of system costs, you are correct that hub height does not appear to affect the estimated balance of system costs when the jacket substructure is selected. If you are interested how that model is formulated in more detail, you can explore all of the code for the model in our open source repository. The specific file containing the offshore BOS model is:
github.com/NREL/ssc/blob/develop/shared/lib_wind_obos.cpp .
Hope that helps!
Best regards,
Janine