It comes with this scale https://amazon.com/dp/B077KC8D8Y
It's the "Weighing Tray" https://m.media-amazon.com/images/I/510Gu4c-hUL._AC_SX466_.jpg
Depends on the amounts and precision. For precise measurements under 20 grams i've always kept one like this on hand. https://www.amazon.com/American-Weigh-GEMINI-20-Portable-MilliGram/dp/B077KC8D8Y/ref=sr_1_7?dchild=1
Goes down to the milligram (0.001grams). Remember the last digit on almost all scales can be off a few points, so I would try to to get one with one additional decimal point than the accuracy of what sh'ed be wanting to obtain.
If you really want to go all out this one goes down to a tenth of a miligram and has an encasing so drafts don't affect the weight. https://www.amazon.com/dp/B01MU940MZ/ But that's probably overkill for most herbs. Actually unless using extracts, the first one probably is too, but always good to have a really accurate scale on hand.
I’ve been using the Gemini 20 milligram scale for over 10 years. ~$30 USD and can accurately measure down to about 20mg. Might be able to find something slight more accurate for around $100 but the difference won’t be noticeable unless you drop several k on a lab grade scale.
Edit prices went up a bit, my bad:
Here is a little kit with flakes of metal that weigh down to 10mg so you can be sure you are accurately measuring small amounts:
