Another way to approach the task of "what should I stock up on so that I can prototype with parts on-hand?" is to look at the range of what's needed, and see if you can pick just a few parts which reasonably span that range.
One example is wiring ("which gauges of wire should I buy?"). If you look at an engineering table of gauge vs resistance per foot, you'll notice a nice little symmetry of 22AWG, 16AWG and 10AWG are each four times more conductive than the last. Just getting these three sizes of wire will cover your light / medium / heavy duty current requirements well. Even the resistance is easy to remember, 16mOhm, 4mOhm, and 1mOhm per foot.
For the 22AWG, just order some solid/single-strand CAT5 cable and you'll have a large supply of nice, breadboard friendly twisted pairs. Having the pairs twisted also does a great job of minimizing EMI pickup for sensitive measurements.
You can take a similar approach for BJT's, MOSFETs, resistor values (e12 or maybe even just e6), capacitor values (e3 is probably fine! 10, 22, 47), etc.