|The scale I use is from Wal-Mart and has a large bowl to place upon the scale. I paid less than $20 for it and it works nicely.|
Seriously, that type of scale is really convenient because the bowl makes it easy to weigh them. Another thing, make sure you set it to zero with the bowl on it...and make sure in between weighing each one that it is at zero before you put a kitten on it...because we are talking very small changes and accuracy makes all the difference.
I agree though, the grey one is very, very, very small and she will need extra care in order to make it. It is really not uncommon for one or two to not make it when there is a large litter. However, she could be a fighter and if you supplement her and make sure she stays consistently warm...she may prove us all wrong. (not trying to sound pessimistic at all, just agreeing that her being small is a disadvantage)