This is often impractical when shipping costs more than the components. Yeah, there are things you shouldn't be buying "just in case" - for example, a stash of

This is often impractical when shipping costs more than the components. Yeah, there are things you shouldn't be buying "just in case" - for example, a stash of SoCs will age faster than you can use them - but definitely buy a hundred of common capacitors, such as 100 nF, 1 µF, or 10 µF, rather than buying them one-by-one. You generally don't need a complete set of all standard resistances or capacitances - there are precious few circuits where you need precisely 47 pF and 6.8 kΩ - but there's plenty of stuff that goes into almost every single project you build. Battery clips, 100 Ω / 1k / 10k resistors, 100 nF / 1 µF / 10 µF decoupling caps, LEDs, PCB-mount switches...