finding old ADF equipment ... where ?

hi folks

my first post to this group, i'm usually over on the sailing groups.
i've been learning a lot about navigation and i want to try some
experiments using RDF (radio direction finding). i was doing some
searches and found out that .. wow, of course .. airplanes used to use
this stuff too! and your equipment is really nice with small bearing
indicators actually showing which direction a transmitter is located in
instead of having to turn an antenna and that type of thing and watch a
strength meter.

so my question is ... besides ebay, where would i find something like
this ? i mean, is there a such thing as like an airplane junk yard ?
lol. besides a very few piloting lessons and plenty of rides as a
passenger i know ZERO about airplanes, so i have no idea where to look.
is there some kind of place around that's likely to have a surplus of
old equipment like this, maybe a place that refits airplanes with more
modern equipment ? reason i ask is i know this stuff is expensive new,
and even used, and frankly i don't want to pay for it, or pay very
little, because i'm just playing around with it.

thanks!