Where can I find authentic bullion dealers for precious metals?

There are pleanty (i.e. GSC) and many others.

Precious metals market in SG is dead, personally that was my first few investment for physical gold/silver, including graded ones like MS69/70 silver panda 1oz.

Yearly there is a coin festival at MBS which you can visit to buy/sell/trade as well. But I have to say market is very very small with most people bleeding like myself (Entered market 5-7 years ago, bleeding ... still bleeding but not dead yet).