just because you got to carry 3 oz liquids don't mean you gotta buy 3 oz liquids. Many US hotels distribute liquid toiliteries in 3 oz containers. many european hotels distribute 100ml(3.4oz) toiliteries. refill them from the larger bottles. I don't know how TSA can tell most liquids apart. I have never seen a confiscation. when I am putting my shoes back on after the foot check, I can see all the confiscated items in bins at the end of the suitcase ramp. never seen any smalls.
drug stores have huge supplies of sealable 90 & 100 ml plastic bottles in the pharmacy. put a perscription label on them if you are really that worried.
for small soap. buy something decent and expensive. they come pretty small, or carry a good liquid soap.