I agree with the previous posts, the 3940 would be a perfect choice. Its a great ship and it comes with _a lot_ of equipment.
But as playmofire mentioned, it might be difficult to get a new one. On the other hand, you can get a real bargain with pirate ships quite often at eBay.
I also would like to bring your attention to this very nice ship:
4444 - Cannon BoatInstead of the 3750, I would instead suggest the following ship:
5778 - Pirate Skull ShipIt basically is the 3750 in a new compilation (speaking of the colors).
And finally, all the corsair ships are somewhat nice. I like this the most:
3174 - Red PirateshipSomehow I have a tendency to red sail...
best,
socrates
P.S.: @Wolf Knight: I pretty much hope that her 6 year old son will not swallow his toys anymore...