[kragen]

At some level it becomes expensive, but it's far from clear that five significant figures of mass is that level.

A US$2 quartz watch measures time to 5½ significant figures, US$10 multimeters routinely measure voltage to 4½, and US$5 GPS receivers can provide you with time measurements accurate to 40ns that inherit the drift of world metrology standards, a precision of 16 significant figures if you are measuring a long enough time interval (over 10 years).

[thirdhaf]

As a quick and dirty rule of thumb measuring parts per million in anything except time or frequency will get expensive. Temperature drifts will cause expansions and contractions on that order if you’re measuring lengths.

[kragen]

Yes, but in this case we're measuring weights, not lengths, and we're looking for 5 sig figs, not 6.

[userbinator]

Where are you finding $10 4.5 digit multimeters?

[kragen]

Hardware store, usually. 3.5 digits is common, 4.5 digits less so.

[userbinator]

3.5 digit ones sell for far less than that (especially the infamous 830-series based on the ICL7106 and its clones). I haven't found any 4.5 digit ones at that price.

[kragen]

I might be misremembering. How much have you found 4½ digit multimeters to cost?

[userbinator]

Around $30 at the very, very least.