I will be in Bangkok next week and I would like to visit a few places that have a good selection of quad copters. It would be good if they were near the BTS or MRT.

Thank you for any suggestions.

Just a heads up and that in January there was a proposal to make quads illegal or highly restricted. Some statements that it may cover only camera equipped versions. Can't find the latest info as to whether it has been enacted yet or not.

http://tech.thaivisa.com/drones-fitted-cameras-banned-thailand/3290/

On the basement level of Fortune Town mall there's a shop that sells quadcopters; not a big shop or a lot of choices but it is very accessible by MRT.

For more variety you should go to Saphan Lek, near China Town, let's see if linking to Google Maps works.... https://maps.google.com/maps?saddr=13.746649,100.504001&hl=en&sll=13.745774,100.504829&sspn=0.004304,0.005987&t=h&mra=mift&mrsp=0&sz=17&z=17

You can get there by taking the MRT to Hua Lamphong station and then walking East along Charoen Krung road for 20 minutes, not worth taking a taxi since there's usually a traffic jam.

The other thing you could do is pick up an issue of RC Action, or the other Thai R/C magazine that I can't recall the name right now... They have many advertisements for shops selling multirotors and everything else. If anything you could browse for what you want, take it to the shop and ask if they can find it for you.