Load cell required with resolution of 1 gram
have you considered finding a cheap gram scale and taking out the load cell out? usually I see them accurate down to +-.1 grams

As stevenh pointed out, cheap scales may not be that accurate, compared to there "box values" If you are just using a load cell from it you should be able to get at least the same and or better accuracy if you have a sufficient design for your ADC and cell combo. 
To get even better results i would suggest getting a small set of standard weights to calibrate your device.