An interesting eBay auction! Not mine. But if you were trying Buchlaesque stuff, it might be usefull.
http://cgi.ebay.com/Vintage-analog-computer-logic-for-modular-synths-etc_W0QQitemZ220497230152QQcmdZViewItemQQptZKeyboards_MIDI?hash=item3356a8b948
Those CES Ed-lab’s trainers are really the same as a Radio Shack 100 in 1 electronic set. Just bananas instead of springs to make connections. They can be found cheap looking in the buisness/electronic section of E-bay.
But for some reason when they get listed as a synthesizer add-on, they go for crazy prices? This guy in Flordia recently auctioned a batch he got from a tech school. He had to lower the $30.00 starting bid because they were not selling at that price. He should have listed them in the synthesizer section. 
Cheap ED-LAB auction for 20 bucks