Go with a beam scale, like the RCBS 5-10 in dryflash's picture. Accurate, easy to use, reliable, cannot drift, no batteries or plugs, blah, blah, blah. Mine came with a Rock Chucker reloading kit that my wife gave me for my birthday a long time ago, and it's still as acurate and easy to use as the day I took it out of the box.
I have two cheap digital scales, and they are good for things like "is this a 115gr 9mm bullet or a 124gr bullet?" but they are not any faster for accurate powder measurements than a good old beam scale. For a reliable, accurate, easy to use digital scale that's worth bothering with, aim to spend at least $100. And digital scales are only as accurate as YOU ARE in calibrating them - which you should do EVERY time you set one up.