27-2s were made from 1961 until the 27-3 came out in 1982. The 27-2 is sought after because it is the last model with a pinned barrel and recessed chambers in the cylinder. All the later Models, including the 27-5, eliminated those features and are generally considered lesser guns.
According to my book, the 27-5 was made from 1989-1992, then another batch of 110 guns was made in 1997. They are good guns, but don't bring the astronomical prices of 27-2s these days.
I'm not really up on prices for 27-5s, but I think anything under five bills would be a good deal, depending on condition.