A Model 14 exists in a place that is similar to other S&W handguns... not similar in price range necessarily, but in a similar place as such models as the 17, 28, 10, 15, 64...
They are simply phenomenal at what they do and are/were so completely successful in the market that S&W made just TONS of them, which tempers their collectibility and/or "value."
This means to own, shoot or love one -- they offer a whole lot of gun for arguably low money. Because for a 14, 15, 17, 28 or 64 to carry a lot of collector "value" it must be in very high condition and/or have some rare or odd factory original features.
The bottom line is that finding one with average and acceptable wear usually means a fantastic value as a gun to own, shoot and love at a very fair price.
I'm not sure that I would chase a 14-7 until I learned what the dash-7 represents (I don't have my book handy and I would almost assuredly be happier with an earlier gun) but even without knowing... I believe I am safe in saying that $550 is a solid buy and offers good value.