There are half a dozen for sail. Great little boat. Give Steve Tribe a call, his details are on the site, and he will tell you all about them. He used to race them in Burnham.
You don't say where you are. Loads of Sonatas in the Lakes and loads of them are for sale. Usually raced so come with good gear.
The downside is sea-going gear is a bit lacking.
Mind you they are not bad little sea boats. I have been for quite long passages in them. I wouldn't get a lift-keeler though, I had one and it sailed like a dog upwind. The bilge keel Duette or later models were much better boats to sail than the lift keel version.
I never sailed a Foxterrier or Chrisma but can vouch that the Sonata is a great little boat, fun to sail and amazingly tough. It can get knocked down in heavy airs but picks itself up, gives a shake and gets on with the job. I've raced on them in conditions that I thought were too bad to take my own boat out.
They are very well known so are probably easier to sell on later if you decide to change.
As Moondancer says, give Steve call at the Snotty Assoc, he has a list of boats on the market.
He's my bruva so is obviously a good bloke. /forums/images/graemlins/smile.gif