In order to sell a lot here you will have to test everyone of them before you sell it.
I've seen 3 of the exact same laser,(50mW 532nm) ordered at the same time, vary in power from 25-70mW. Just because you test one and it measures up to spec, does not mean the next one will come close. Quality control is so bad on these cheap Chinese lasers.
mW output is only one of the indicators of a good DPSS laser. You also have to take into account, divergence, stability, mode hopping, beam profile, and duty cycle vs. lifespan.
Only after all of these parameters are checked, can you be assured of buying a good laser.
Of course if you buy 500 in one lot, and the first 50 all measure close to the same, in all parameters, it's a pretty good bet the rest will be close.
Bottom line; you'll need to do a lot of testing (and have quite a few testimonials) before we will accept your products as good quality.
Good luck!