You probably want a lab-quality scale. Here's one that seems to get a lot of mentions:
A&D FX-120i
http://balance.balances.com/scales/1223
I would not go with any of the scales marketed by the reloading manufacturers. There is no guarantee that a $300+ scale from the usual suspects is any different mechanically or electronically than the $30-$50 pocket-sized scales you see hanging on the racks at the local gun shop.
If you are serious about digital, look for one that has some sort of lab-grade certification.
Just some thoughts.