So, where might someone find the turn plates and guages to get setup at home? I am a retired tech and have done many alignments on a "machine"
All kinds of places. Summit sells the Fastrax caster/camber gauges as well as the longacre magnetic types, as well as a whole bunch of different toe plates.
Turn tables can be found on Amazon or eBay, ranging from cheap to really expensive professional versions. And you can always find stuff used, probably the best deals are for used professional stuff.