RDS
RS Components sell a Kern scale (440-33N) that uses Kern's own serial link program to graph weight against time. It comes in for about £300. That model has a high resolution for accuracy checking but the price you pay for that fine resolution is it only goes up to 200g so it's limited for recording overnight runs.
I was investigating scales a while back but didn't in the end take the plunge. Sartorius used to do a setup tailored for pump testing but it fell by the wayside. Now they just do a serial link & weigh software but it cost some £1,600 due to the laboratory grade scale they supply for the purpose.
All the best
Marc