One thing to consider with a turn-in revolver...it's very likely to be double action only. All you'd have to do is swap out the hammer to fix that if you don't want a DAO revolver. It's not hard to do, but it you can't or don't want to and want the traditional SA/DA trigger you'll need to factor in the cost of having it done.
That said, they can be and frequently are great deals. They'll probably have some cosmetic defects from being carried, but many won't have had a ton of rounds fired through them. I picked up a S&W 67 over a year ago, new grips and some polishing and it looked almost brand new for a lot less than it would have cost had it been in that condition to begin with.