As others have said, .357 revolvers will shoot .357 mag or .38 special. But if you are thinking you'd just like to stick to .38 special and the gun won't be pocket carried, then you do have some really great choices in larger .38 revolvers. As much as I like my 642, for me it is a niche gun (pocket carry ONLY). For home defense, or carry IWB, I prefer larger heavier guns that point more naturally. But YMMV.
A couple of examples...
Depending on the exact model, a 4" .38 Special S&W K Frame can be had anywhere from $250 to $450. So you can likely find one for less money than a 642, new or used. My 15-3 4" is an excellent example, made in 1969. I picked it up in May '09 for $309. Right now, it is one of the best handling/best pointing handguns I own.
The Ruger Six Series revolvers (Security Six, Police Service Six and Speed Six) all make great home defense / carry guns (most are chambered in .357 Mag, but some came in 38 only, while fewer still were made in 9mm). I saw a table full of .357 Police Service Sixes (square butt, fixed sights) at a gun show priced at $299 each. I picked up this one for $275 a few months ago. One of the best all around values on the used handgun market, IMO.
Though there is something to be said for snubbies, in that they do present a bit less barrel for an assailant to grab onto. I've always liked 2" S&W K Frames for this reason. Being that they are all steel and fit my hands better, I find them easier to shoot than the diminutive J Frames. My .38 Special 2" Model 15-2 (made in '65) is one of my favorite all around guns (however, it is NO pocket gun). Paid $375 for it about a year ago. Actuallly, I shoot it just as well as my 6" Model 14.