Sorry for the delay.
Ferry for 4 was 288 EUROS, upgraded car rental for a SUV on St Barths was 60 EURO thru Voyager (the same day I book the ferry) (1.10 was the exchange rate so 348 EUROS times 1.10 equaled $382.80). The SUV for St Maarten thru avis was $440 but we insured another drive so I think the total without the extra driver was $384 for a RAV 4.