6"? 4"? Box/Papers?
Worth? To a LGS, maybe $500 on trade. To a private sale, $750+.
Some people (like me) love the pony and will ante up depending on condition, age, accessories, etc. Others... meh.
ETA. a Colt for a Glock? I'd do it. The 357 is closer to your 9mm family, just a little longer and noisier.