Any good digital kitchen scale will do fine as long as you don't care about weighing all your grain in one go -- they usually max out at 11 lb/5 kg, and once you tare your bucket, that's under 10 lb of remaining capacity. But I just use my kitchen scale and a 2 gallon paint mixing bucket and weigh my grain in two or more lots, dumping each into the mill hopper as I go, so I don't have a redundant piece of equipment that just gets used on brew day. (If you don't have use for a general purpose kitchen scale, ignore this post. I'm sure somebody can recommend a good high capacity scale.)