The '83 vintage 6.5" M24's appear around $400-$500 used somewhat irregularly of late. The '01-'02 vintage 'Heritage' series 24 is also a possibility - CDNN had them earlier this year for $600 new. I have one of those and an older one, a 'LNIB' twenty-year safe queen '83 24 which had more QC problems than all of my other S&W's combined. The N-framed 24's have adjustable sights and, especially the H24, a finer blueing reportedly than the new MSRP $958 21-4 TR special.
I did buy a 629 MG several years ago as just a '.44 Special'. Okay, it doe see some .44 Russians, too. My latest 'toy' is a homebrew of sorts. I really like my 4.6" SS BHG Vaquero in .45 Colt and wanted one in .44 Special. I ordered a .357 Vaquero BHG for a conversion, but lost my nerve when I found out what it would cost. I bought a new 4.6" Super Blackhawk and a QPR BHG and fitted it... what a treat! I now have a .44 BHG - with adjustable sights, a real boon for .44 Special use. Sure, it, like my 629MG, says '.44 Magnum', but to me, it's a .44 Special (and .44 Russian). That SBH in 4.6" is so nice, I may have to get one and a Bisely gripframe...
Ammo is a problem - unless you reload. My 296 is highly ammo-restrictive - and the Blazer 200gr GDJHP's, at $12.99/50 at a local sport's chain, are both ideal and frugal enough for plinking in my 696, too. I now buy the Georgia Arms similar all-new ammo in Starline cases - you get some nice reloadable brass that way - ~$18/50. Oddly, both are less dear than local Cowboy loads (~$20/50). I reload... problem solved.
The .44 Special is special... the .44 Russian, even more so. Try to find anything chambered in THAT (Okay, Navy Arms still makes the S&W Model 3 .44 Russian clone...). The use of a .44 Magnum revolver is about the only way to get a 4"+ these days.
Stainz
PS The 3.1" S&W 396 is reportedly still in the catalog... adjustable sights, too. ~$600