Well you're looking for answers to what you apparently think is the high price of a Hells Bay Marquesa model, and to me it does not sound like you know too much about what you are asking?
The $10,900 Hells Bay you mention was the Whipray, one of the first models they came out with. This small $10,900 model came with virtually no options and a 40hp tiller drive as I recall. So what's wrong with that price, as the Whipray was their entry level boat?
Comparing a basic stripped down Whipray at 10 year old prices with the price of a Hells Bay model today that has essentially become the Cadillac of flats boats is equivalent to comparing a Chevy II or Chevrolet Nova to a Cadillac.
FYI, material prices (ie. fiberglass, kevlar, resins and gelcoat) have gone up close to 100% since the $10,900 Whipray price you mention, and the $43,000 price of today's Marquesa sounds quite reasonable to me.