Whether milling spice or changing fruit or (the one that I'd REALLY love) making compounds, have a similar "you already have this much" info as was recently added to vendors. I'd especially love it for compounds since going over the 250 stack can be so messy. As it is, I open my alchemistry kit and do the math... but I hate math.*
*Not true. I like math. I just like to save it for special occasions.