Well, now that I've finally done the math fully, the wereferret would be cheaper if his natural form is the Ferret.
The baseline domestic ferret costs -74 points. Making the IQ 10 again makes it costs 49 points. Removing the Hidebound limitation from Domestic Animal makes it cost 54 points. And the human template is worth 0 points.
In effect, my character concept has gone from wereferret psychic assassin to a werehuman psychic assassin, which amuses me greatly. Oh fun.
In any case, this saves a chunk of points which I can put into something more deadly. A ST boost for his jaw, and more psychic powers.