Conversation so far:
What is the H-4 hercules?
The Hughes H-4 Hercules is a prototype strategic airlift flying boat designed and built by the Hughes Aircraft Company.
What was the use of the H-4 Hercules flying boat?
HK-1 Hercules flying boat was to be used to transport troops and equipment across the Atlantic as an alternative to seagoing troop transport ships.

Question: How much did the hercules cost to make?
Self-contained rewrite: How much did the H-4 Hercules cost to make?