Try cruisecompete.com as a starting point (or near melting point for you
) to compare rates. Let travel agents shop for your business, and you'll get a sense of the prices out there.
I just booked my 1st ever cruise for a sailing in August. A whole lot of $$ out the door, but after diligent shopping around and homework, I did find a better deal than I would with NCL directly. Nowadays, I email my travel agent with all sorts of questions, and she's always there to help.
And I think a 14-day vacation is a-okay! Sounds fabulous in my mind. But will you miss your own bed for 14-days? Are any of you prone to motion sickness? Prefer your own cooking? Dislike others doing your dishes? Those kind of things. But you'll be fine.