As far as walkers go, that is a nice-looking one. I like that he's standing quietly in the water as well. Age is good, conformation looks good, from what I can see in the pics. I expect he has been lightly used. His rider (owner?) isn't a 500 lb gorilla. All that speaks well for him. Before you go to see him, I'd decide what my top-dollar was, because once you decide you like him, you're going to lose leverage on the negotiating table. Remember, they wouldn't be selling him if they didn't want to get rid of him. Look for hoof problems, leg problems, ask whether he's ever been injured or lame. Lift his hooves, mess with his ears, saddle him up, see if he's cinchy, etc. Is he lazy? How about unwilling? Obstinate? Happy? Ornery? A horse that age is sometimes difficult to retrain out of bad habits. Soft eyes are a good indicator of a good disposition.