Most of your parts inventory can be salvaged from old circuit boards
In order to build an electronic circuit from plans or from scratch, you will need a number of semiconductors and components. Often, these individual components cost only pennies new, but in order to purchase from a large supplier there will be a minimum order number or price level that has to be met. It would seem crazy to pay $25 in shipping to receive a few 10 cent capacitors or resistors, especially when you can salvage them from just about any old circuit board. Almost all of the components I use are salvaged from old boards. I don't think I have ever had to order an odd value resistor or capacitor as I have always found what I needed by scavenging my huge junk pile.
A few dead TV or VCR circuit boards will net you enough raw components to fill an entire electronics parts bin, and allow you to experiment with varying values as you breadboard a new or published circuit from a schematic. Almost any discarded appliance that includes a power cord will become a great source of raw semiconductors, so tell everyone you know not to throw out their broken appliances, send them to your mad scientist lab for dissection!