+1 for a 19/66, or 586/686. I have two 66-1s (one 4", one 2.5"), a 19-5 (2.5"), a 67 4", and a "pre" 10 from 1946. The 67 in .38 special has a wonderful trigger and is sweet. The pre-10 (Military & Police as it's called) is 5" and just feels like history in your hands, and handles well - the 5" barrel balances better on that frame and with the tapered barrel (holsters are a bit more problematic, albeit). You can buy holsters all day long for a 4" or shorter K frame for $10 a pop.
I also have a 686, built on a (very) slightly larger and heavier "L" frame. It handles a variety of magnum loads better and is slightly more robust, but I like the feel of the K frame better. the 686 may be hard to get under $400, also. Oh yeah, NEVER shoot a magnum load lighter than 158gr in a K-frame. You can damage the forcing cone or do serious flame cutting damage to the top strap fast. Check out the discussion at the Smith-Wesson forum if you don't find details on that in this forum if you are interested in that problem.
The snubbies are just awesome. The round butt lets you get an awesome finger-groove combat grip for a great feel. The 2.5" barrel gives up little in accuracy or recoil to the 4". The white outline sights and red ramp are a fast acquisition package. These 19/66 (66 is just the 19 in stainless, ditto 15/67, 10/64, and 586/686). The 19/66 snubbies are just awesome carry guns if you have a cc license. More punch than a .45 acp and if fits easily under your shoulder or in a pocket (I am a HUGE 1911 fan, so I don't say this lightly!).
You should be able to get any of these for $400 if you shop and haggle hard.
If you don't want or need a magnum, a 15/67 in .38 should be commensurately cheaper, like $300 or $325 in great shape.