Thailand is a great place for scuba diving with the Gulf of Thailand and the Adaman offering two very different types of scuba diving adventure you can find lots of scuba diving in Koh Toa and the Phuket Ko Phi Phi areas and diving in allot of other places as well like Koh Chiang close to Cambodia or down near Penang Malaysia sea scuba divers have lots of options lot of options to buy scuba equipment . Thailand has major wholesalers located in Bangkok and Phuket that sell to the majority of dive shops in Thailand as well as Cambodia,Vietnam and Burma.
They sell Mares and Coltri Sub, Thailand is also the home for ocean concepts a local brand that sells some good masks and other dive gear like dive guages. they also sell coltri sub Compressors they re the regional representive.
If you are looking for used dive gear head down to Koh Sahn rd as many people are looking to get some quick cash and to lighten their backpacks before they catch flights out of bangkok new airport