Over the last couple of decades I've built, bought, sold and am building another now on the island. I've watched them rot and seen them blown away but still want to own my pier and not pay rent to dock my boat or have someone impose silly rules on me about how I should manage my affairs.
PVC post and stainless nail are very sensible, but $200.USD a foot can't be a realistic meter of cost because the length or the pier determines how much a foot. Imagine buying a 10 foot dock for 2,000. dollars :-) but a 100 foot dock for $20,000.USD is a good guess for a quality dock. however if your property is in front of a lot of shallow water you may find yourself needing a 200 foot dock to reach water deep enough to float your boat. That 200 dollars per foot figure should then decrease.
May I also suggest a dock that is constructed in a matter where it can be partially disassembled before hurricanes for tropical storms. I've actually noticed quite a few docks north that were constructed where removing every other deck board was almost impossible. No bueno.