I am employed as a service engineer for Chicagoland's largest industrial and laboratory scale distribution and service company.
During scale selection, there's 2 performance characteristics to be addressed: capacity and graduation size. Start out by evaluating the grad size you need, then see what capacities are available.
To determine your capacity range, bear in mind that this is the sum of the material being weighed AND the container the material is in. For a kitchen scale, most ingredients can be divided and weighed in portions so as to stay below the capacity of the scale. That Pyrex beaker or stoneware bowl is probably pretty heavy so consider lighter containers for weighing.
In general, the measure of a scale is the number of displayed divisions it will show you. The scale
MikeLM mentioned has an 11lb=5kg=176oz capacity with a 0.1oz graduation size for 1760 displayed graduations. While probably sufficient for most kitchen use, in my profession this would be considered ..umm.. junk and certainly not meeting
jpchust's requirement for high accuracy in an experimental application. Everything else equal, the cost of a scale increases with the number of divisions. In the biz, we call a weight measuring device with greater than 50,000 (or so) displayed divisions a
balance.
There's usually a substantial price jump from 0.1g to 0.01g division size. This is because the more sensitive balances use a much more complicated mechanism (magnetic force restoration/load compensation) for measuring the loads than lesser scales (using load cells/strain gauge transducers). Watch out for some gem scales that look great with 0.01 or 0.001 g resolution but are very low capacities. For accurate measurements of things used sparingly in the kitchen like herbs or coloring agents, I think you're looking at a 0.01g grad size.
These may get kind of expensive. My personal kitchen scale is 1300x0.01 grams...130,000 displayed divisions. This stickered for around $1200 new.
*ETA: Very high end but off-the-shelf balances will give you 20 million+ displayed divisions. $12,000. Food for thought.*