ohaus and tanita are both reliable brands. Can find them at most head shops, and cheaper ordering online.
Far as which one, the main things you're looking for are max weight, resolution (does it distinguish 10ths of a gram, or 100th's or just grams?), they should also indicate the accuracy (something like +/- .01g). Make sure it will measure the quantities you need to measure at once (including any container you use to hold what you weigh). The higher the resolution (or smaller changes in weight it can distinguish between) the better. The more accurate the better. Then look at price, obviously you will have a budget, so stick to it. A few other things, consider the weighing surface, is it large enough to fit whatever container you use to hold it, or if you want to weigh directly, could it hold what you want to weigh? Auto off, etc. Anyway, look at the specifications and prices and make a choice, but I would stick to one of those two brands.
