Kind of hard to find now days but I have seen them around 200 -250 when I did. I myself got two barreled actions from Nartron. One was like new and matching the other was good condition with a little rust and mismatched bolt but both headspaced well. I then ordered a nice russian stock for the good one and an aftermarket for the second one. The actions were like $49 each I believe.
I'm loosely basing my price on info several years old, "adjusting" for inflation, so I may be off (too high, if anything). I haven't been actively researching or collecting Mosins for about 5 years now, though I did buy an ex-PU sniper two years ago.