...on a lot of variables: fixed keel or swing-up? inboard diesel or outboard? standard or tall rig? dinette interior or standard saloon? Pop-top or no? Mostly, what year and what condition? Is an survey available?
One way to compare prices is the Auto Dealers' Web site: Used 1986 CATALINA YACHTS 25 prices, specs and options at NADAguides.com
The Catalina 25 is a great all-around coastal cruiser but I wouldn't take mine on an ocean voyage. It's good for an overnight or so, but as a boat for liveaboard, the headroom would become an issue.
Check out the Owners' Web site, too: Catalina - Capri - 25s International Association