You've gotta watch those electronic scales from Amazon. I bought one a year or so ago and later found that it is exactly 1.5 grams off across the board. Haven't found a way to zero it although you would think there would have to be one. The electronic scales can work but you have to make sure you get a good one. Some are and some are not. I got a brand called AWS. Probably not the best. Thankfully I did not pay much for the scale although I messed up a few concoctions with it.
For a few dollars more, careful shopping on the auction site will get you a used Ohaus triple beam balance. There are other brands that likely work just as well for our purposes. I paid right around $30 for mine. Little cleaning and it is just like new and right on the money every time.
If you want to mix developers and such you really want a respectable scale. Top of the line is not necessarily needed though.