Its really not that bad ,
just be sensible and as ready4 said ,
get advice from and hang out with someone that lives there ,
better still , go next door to cambodia or laos if you want to avoid the strict thai rules on gunja ...
last time i scored in thailand ,, i guess about 7 years back ,
i got 4 ounces for $80 Aud ,
only the compressed brick weed , but its not too bad really ...