by Brian Tivol

Answer: TUNIC

The five-letter words are like Mastermind guesses against the word
TUNIC; each item initially costs $1.00, with each white peg adding a
dime and each black peg adding a quarter.

Striking out all the letters in DERBY, DORAG, and SHAWL, we see that
SHIRT's two matches must be I and T, while THONG's two matches must be
T and N.  This means that the F in SHIFT must not be a match, and
therefore the three matches in FICHU are I, C, and U.  This gives us
our five letters, and it's clear that no other letter matches.

The black peg in LEVIS nails down the I.  The black peg in THONG
cannot apply to the N (because the I goes in that spot), so it must
nail down the T.  With the T and I in their places, it follows that
MUFTI's black peg must be for its U.  KANZU's black peg must fix the
N.  That leaves only one place for the C.