Maritimesailor:
That is a reasonable price range for a used boat. The boats that I would recommend you go with as they are the more proven ones lately are the Tiger, Infusion and Capricorn. I think the older Nacra F18 is a fine enough boat. My hesitation would be that it has a softer mast so it loses a bit of power on the lighter days. I think someone put a stiffer mast on one, I do not remember who, and I think that would work magic on that boat as well.
As far as sails: We have a couple of guys on the West Coast sailing with the older cut of Tiger sails and doing fine. They are great sailors though. It is hard to say whether the newer cuts are faster in all conditions.
Contact the Quebec fleet I am sure there are some used boats there you could get hold of. It is a good group of sailors.
Later,
Dan