There's also the various "gunbuster" sellers on GB that sell everything but the frame as a package. I believe I saw some last time I had reason to go looking for parts for another project.
I've (mostly) stopped chasing the "perfect" carry and HD pistols. I didn't try any Sixes during my 4" .357 rabbit hole journey and since none of the others grabbed me enough to be "keepers", I'll probably take a trip down the Six trail next year.