Hi xavier 
Nice to hear about other peaple having the same project. Do you only store the data from your scale, or do you have some method for reading the weight remotely?
An update on my work:
I made a prototype using this load cell:http://www.aliexpress.com/item/100kg-200kg-300kg-weighing-scales-load-cell-for-platform-scales/624403255.html and the ina122 amplifier. This setup gives me a great accuracy and almost no temperature drift. However, the ina122 is getting a bit unstable when I am powering it with a 3v battery, so I am going to try some other amplifiers like the ina333 or AD8553.
LEGO-lars