Go here for a good quality scale for the price.

http://www.oldwillknott.com/6001tblu.html

about 50 bucks and scales up to 13.5 lbs and as low as 1 gram

There are cheaper scales out there but for quality measurements this one works great.

Now if your into measuring epoxies for the right mix you will have to step up to more expensive units or a triple beam scale.