Been there, done that... it's worse than finding out you have a flat tire at 5am I'm with Tam... I try not to go less than 60ml of my ADV before buying more, or mixing more... Mixing is not an issue, because I can whip-up a batch quickly, but if I'm buying something pre-mixed (or need components for mixing), I try to order it way before I need it to allow for shipping, out-of-stocks, back-orders, etc....