I agree with most everything said above. If you have a single pet or two then you should be seeing your animal enough to tell if it isn't doing well. When you are breeding, selling, or own lots of snakes I think it is a great idea to have a scale for records. I even record the size of meals if I have the time. That being said, overall, I think as a responsible owner everyone should have a scale. I bought mine from Walmart for $30 something dollars and it weighs up to 5000 grams.
Regards,
B