I use the same scales I sell on my site:
http://www.coppercave.com/copper/index. ... &Submit=GoThere are places to get them a little cheaper, but I keep a couple in stock for customers who are ordering other stuff from me anyway, and I get asked about scales from time to time so this way I have something to point to. I also stock the appropriate calibration weights.
Nothing fancy, they have a bigger platform than some "pocket scales" but still have a nice hinged lid so you can handle/store/transport them without putting unnecessary stress on the platform. The instructions are also printed on the inside of the lid, always there whenever you go to use it. They just use regular AAA batteries, no little watch batteries like some, and you don't need a screw driver to replace the batteries.
I like the 100 x 0.01g scale for weighing fractional and 1 oz pieces with a little more accuracy, and the 1000 x 0.1g for the heavier items like 5 oz and 10 oz bars.