It really depends on a lot - and Jaco is more expensive than San Jose (In SJ, I'd say $100 - 150)
I'm gonna throw out something for your (re)consideration:
Do you really want to pay a bunch of money for them to sleep???
Bringing them out on a charter (some will disagree;and that's OK - you will make the final decision; your money and your time) is one of those things that sounds good but can turn to shit - the girls, known for other talents vs their fishing prowess, can become real pains in the ass on the boat -
Guess you can tell from the post that I'm not a fan of all nighters, nor taking girls out on a charter
Let me play "Carnak" (Are you old enough to remember him; it was a character played by Jonny Carson, where he guessed things contained in an envelope - was pretty funny) and guess the following:
You are fairly young
You have a decent job and make a few bucks
All this is new to you
Am I close?
PS Nothing you are asking about is weird or out of the ordinary - some guys love to do what you posted about, and that's fine - I'd tell you to reconsider - even if the money is a minor concern, especially on a charter.
If you say, WTF, I want to have company on the boat, and the mate does not count

- make sure you ask the captain and clear it with him first.