There was once a set on eBay that were the old fashion balance scales complete with all the weights. I bid on them but someone sniped me at the final minutes.
I have a set of pallet scales that are digital, they were bought new and they have been a real problem. I have had them worked on twice and they are currently non-functional again. Based on my experience with "electronic" scales, I wouldn't buy them from eBay.
Just my opinion.