I know, I know, it's frowned upon, but hey: I'm trying to buy a F16, and my Nacra 5.2 with spinnaker is up for sale. Old, but in your price range, can be sailed solo or duo. pm me if you're interested.
I have to say that I nearly added "or any other odds and sods like the smaller Nacra's would also fit the bill".
A 5.2, assuming it is in sensible nick (no offence intended Pepin), would also be a good option.