When I make a parts order I always add extra IC's and whatnot. Need 1, grab 3. I try to keep every resistor/cap value on hand, replenish as they get low. I'll buy enclosures and pots per pedal.
Usually I wait until I have a bunch of pedals on the horizon, make my order, then reorder the parts I missed the first go. Add extra shit to make the shipping worthwhile.
And in the spirit of Popnfreshbass, I got a couple oz of mushrooms stuffed in a kitchen cupboard...