Look at it from the other way around:
At this dosage, it does not matter if you use 0,02g or 0,1g. The amount used will be minimal and a decade's supply can be had for pennies. Use a little more and don't weigh it. Reducing agent does not have to be exact.
But I will say that for making colloids, a jeweler's scale will come in handy sooner or later.