Where in Bangkok will i be able to purchase a macro lens rail ?

i hv a sony a200 slr with which i do macro photography.my macro lens is a konica 40mm reversed lens mounted on the camera body.As it is not af it is very tedious to fine focus the subject by adjusting the camera on tripod or hand held. I want to purchase a 4way macro rail , which is not available in delhi-india where i live. My parents are visiting bangkok next month. I wanted to know where they would be able to get it at bangkok. If possible do furnish the name and no. of the store so that i can call and confirm price and availability. thanks