>Now-a-days, how does a kid build anything of their own? Where do they
>get parts?
Any which way they can! There are a lot of fora on internet which are used by youngsters to share information and buy parts together from companies likes Farnell, Digikey, etc. Same goes for measurement equipment. If you buy 20+ brand new oscilloscopes at once (not joking!), you can knock quite a bit off the price.