If homophones are the pattern to follow, then (since a large collection of legitimate stores can be thought of as a "mall") perhaps the new word should be "a ma

If homophones are the pattern to follow, then (since a large collection of legitimate stores can be thought of as a "mall") perhaps the new word should be "a maul" or "a mawl" (suggestive of being something that swallows your money, and doesn't give you anything of value in return).