Hi Peter,
Any scale that can show grams OR ounces will work for you, depending on the size animals you keep. My biggest hondo is about 1,335 grams, so a 2 kg scale would be fine for my purposes. y9u can figure out relative to that what the max capacity needs to be.
baby pyros can weigh as little as 5 to 7 grams, baby hondos 17-24 grams, my scale weighs to the nearest gram and i've never felt any need for precision into the tenths of a gram. there are around 28 grams to an ounce after all, so accuracy to the nearest gram would seem fine to me.
two good sources for gram scales: office depot/staples kind of office supply stores; or food/restaurant supply stores.
good luck! there's a lot that can be learned from maintaining weight records. a fascinating exercise is to weigh hondo females out of brumation and two months later. They pile on the weight with amazing rapidity prior to breeding.
peace
terry