I use the Acaia pearl scale - http://acaia.co/, but you will probably balk at the price.
Agreed with AY that experimentation is key. Make small changes to one parameter at a time to get an idea of the results. For example, increase / decrease grind size by 1/8-1/4 turn at a time until you find your sweet spot. The do the same with brew time, water temperature, etc. You will eventually be able to correct for different beans or brew methods pretty quickly.