I had a 19 that wouldn't group even Remington HBWC less than 3", just won't do it. I sold it. I had a Security Six that wasn't much better, traded it. I had a Rossi 971 that was a little better, neat size for carry afield, but had some firing pin problems with it, traded it. I have a Taurus 66 now that will group WCs into 1" or less at 25 yards, I'm happy. Now, any .38 will function in a .357 gun, but not all guns will group them worth a toot. If 3" groups at 25 is dandy for you, well, you're okay. About any wadcutter load will do that. Me, I wanted to be able to hit a rabbits head at 25 if I did my part. My 4" .357 is an outdoor revolver. I care more about what Magnums will do and I ain't so finicky about accuracy in self defense guns. My SP101 snubby groups about 3" at 25 and that's plenty fine for self defense. More importantly, it seems to do really well off hand for shootability.
The cheapest ammo will likely be 130 ball, the most accurate I've ever fired factory loads is the Remington HBWC. Out of my M10 Smith heavy barrel chucked in a ransom rest, it'll shoot five shots into a ragged hole at 25. I've won a few revolver shoots with that combination.