[Junk_Collector]

So one of the neat things about Analog computers is that you get a lot of kick out of "simple" circuit designs. All you need to reproduce everything in the handbook is a bread board, a power supply, and an oscilloscope for output. You can get the individual components from Ada Fruit, Digikey, Mauser, and more. Depending on where you live you can even pick them up locally. Fry's and Microcenter being the two biggest chains that still stock opamps and the like.

If you don't even want to hassle with all of that, then you can look into something like the Elenco electronic playground for $50 which has most of what you need mounted and then you just jumper, ala the old analog computers.

If you wanted to get really advanced, you would want to go to something like the guys at https://www.xmicrowave.com/ make, but that gets awfully spendy on a hobby budget.