Thailand's government has warned clothes vendors against inflating the price of black garments amid a rush on outfits to mourn King Bhumipol Adulyadej's death.
Since the death of the revered king this week, market vendors and retailers have been doing a brisk trade in black clothes.
Markets have been packed and surrounding streets jammed as Thais stocked up for a year of official mourning.
But the Commerce Ministry has asked clothes sellers to keep prices reasonable.
Thousands of people are expected at the Grand Palace today to sign a book of condolence.
While the monsoon rains have so far stayed away, the intense heat and humidity has been problematic, with at least 200 people treated yesterday.
Meanwhile, Thailand has also warned foreign media against reporting what it called false and provocative information about the death of the king.
Thailand's Ministry of Foreign Affairs said media should not be reporting what it called erroneous and manipulative information that offended Thai people in national mourning.
The ministry did not specify what the offending reports were, although a New York Times story published details about Thailand's Crown Prince that are usually taboo.
Under Thailand's strict lese majesty laws, any perceived defamation of the king, queen, heir-apparent or regent can be punished by lengthy jail terms.