In the S&W terminology, a gun made prior to 1957 typically is a "named" gun and often referred to as a "Pre-"[model number] gun.
The gun you're asking about is the .38/32 Terrier which was built on the I-Frame (which preceded the J-Frame). It can also be referred to as a Pre-Model 32. It is a .38 caliber revolver built on the S&W .32 caliber frame.
Postwar I-frame revolvers ("I-frame") saw a lot of design changes in a short period of time. Early specimens are (almost) look much like their prewar predecessors. The early configurations uses a flat mainspring. Soon after I-frame revolver production resumed in the postwar years, the company went to a coil mainspring, giving rise to the term
Improved I-frames.
How do you tell which mainspring you have? Well, you can take off the grips and observe directly. You can also tell it's a flat mainspring if you have a screw and the front, bottom of the grip frame. That is the strain screw that tensions a flat spring. If there is no screw, you have a coil mainspring.
It's also important to note that the Terrier is NOT chambered for .38 Special. It uses the older, less potent .38 S&W cartridge (see photo below). The two cartridges are not interchangeable. That said, the .38 S&W is a fun cartridge to reload. It takes little powder and is mild shooting. But out of a 2-inch barrel performance is quite lackluster.
.38 S&W vs. .38 Special
$500 sounds a bit on the steep side, unless it's in nearly pristine condition with the original S&W box and tidbits that came in the box.