Or the i170 offhand: the upgrade from i140 OH to i170 offhands produces the same stat boost as getting the i180 mainhand.
In my own case, my wife and I bought red scrip i180 BSM, CRP, and i180 GSM mainhands.
Having BSM+CRP+GSM mainhands lets us make the offhands for all the other classes, at which point we will be able to do all the 2-star crafts.
Capping red crafter scrip takes about 2 hours, if you wait for a gold star on something easy. I prefer it to the 2.x grind for Oaknots, myself.