I got one of those Escali Arti glass top kitchen scales (a Groupon Special) and it does very well. But any kitchen scale that can weight in grams should be fine, even if it isn't crazy accurate for those small amounts. The hops are probably where you end up measuring out 2-5 grams. You can eyeball the size of the heaps too, they should be about even.
The main part you got to make sure, if various ingredients are pre-mixed, is that the mix is homogeneous, so you don't inadvertently scoop out 2 of the 4 oz C120.