Double-ended or canoe-sterned center-cockpit boats are not too common. Besides that Westsail 42 (or is it 43?), another is the Corbin 39. Most of the Corbins were aft cockpit with pilothouse (
like this one), but there are a few center-c versions around.
Other center cockpit boats possibly in your price/size range are the
Whitby 42, and the
C&C Landfall 43.
A couple others possibly worth exploring are the
Peterson 44 and Peterson 46. The 44s especially are getting on in years. Also, there are other Peterson designs of this length (44/46') so don't confuse them with these center-cockpit ketches from the mid-70's to late-80's.
If you want to look at some newer boats, Beneteau has
a 36CC,
the 42CC, and
the 44 center cockpit. The 36 would be in your price range, but the larger boats -- maybe not.
Others will have more recommendations, I'm sure.
Oh yeah, thought of another. Amel has made many models over the years. They are pricey, but some of the older
46 Maramu and
48 Maramu ketches are now getting down closer to your price range. There was also an earlier model, called the 46 Santorini, I think. Maybe in a few years?