Spotted some riding boots in the second hand clothing shops on the way to Tesco North of town, a pair of red and black Sidi's small size suit a lady and a pair of red Diadoras about a 9 or 10 size and a pair of white ankle high riding boots, priced between 1000-1400 baht. Another store had a 2 piece leather riding suit a bit small about 3000 baht