I also hit the phone book yellow pages immediately in new towns, but also I
try to use Yahoo yellow pages at home before I leave so I can print out
some lists of places.
Thift stores and pawn shops are so unpredictable, and often pricey, so they
are not the first place I look.
USED computer dealers, computer recyclers, now that can be some good stuff.
Scrap buyers, same thing.
Hamfests, ie in Los Angeles on the last Saturday of the month there is a
big one at TRW.
Visit the local members of this list. NOBODY that has visited me so far has
left empty handed, and my garage has a better selection than most stores of
any kind.