I good idea is to check HOW they sell the stuff, I've been in Thailand for 8 years and they are horrible liers/ marketers.
- Check the catalog and see if it's a ordered catalog or home-made with cut/ copy, the later is a bad sign.
- Check the prices, too expensive usually means fake. Legit shops value returning customers and don't need to add prices.
- Check the seller, does he look like a moron when he tries to sell the stuff to you.
- Ask him what he recommends, if he clearly makes it up, then back off.
- My experience is that the cheaper the box looks, the worse it is inside. Even if it's not totally legit, a seal usually means that they put effort in making it.
Every cent counts in Thailand.
- A good sign is if you ask "do you have AAS here (say steroid, they don't understand AAS usually)" and they answer "No" or "Who told you that".
They have countless of raids and the only thing holding them legal people out is bribes - which in turn means they need returning customers and value discretion.
Sorry that I can't tell you anything on the brands, but above is a good "know-how" when it comes to shopping in Thailand. Seems tho you have it all set!
I know a few places depending on where you are.