A pristine Catalina 25 can be had for around 10K. However, your tow vehicle is not up to the task. Boat and trailer will be 6-7000 lbs, loaded, probably more. Cream of the crop years are 1987-1991, with a wing keel. Swing keel models are also readily available, they are trailerable, but require a little more maintenance.
The Catalina 25 International Association can be found here:
One of the members has this boat for sale: