Thailand is known for its counterfeit. In terms of pictorial art also, copyists do an outstanding job and you will find many small galleries in Phuket, where more or less experienced painters can reproduce your favorite paintings at reasonable prices.
But if most of the galleries exhibit reproductions of famous paintings, there are some genuine artists who have enough inspiration to create their own works. For this reason, we recommend visiting Phuket Art Village, which includes at the same location several galleries exhibiting Thai artists from Phuket but also from the rest of the country.
Some antique stores also sell paintings of past and contemporary artists.
Fortunately, you do not have to carry your painting at the airport as most shops offer to send you the painting directly by airmail.