Can I DCA into ETFs at low brokerage cost?

Yes, there are different options:

#1 cheapest one (0.00 USD) fees: brokerage account with TD Ameritrade or Charles Schwab (attention: soon both companies will be merged under Charles Schwab label); no commission fees, no account fees = superb! Only thing: U.S. dividend withholding tax (30% or 15% will automatically subtracted from dividends, but not from capital gains (when you're not a U.S. tax subject)

#2 some nice Singapore online broker (like POEMS), compare their fees, U.S. is avantgarde, and many countries will follow towards 0.00 commission fees.

Hi yes,you can do it via posb invest saver

Summary:
1.investing $100-$500 per month use posb and Maybank
2.investing $500-$1000 per month use OCBC @3%,min $5 or Maybank @1%,min $5
3.investing $1000-$3332 per month use OCBC @0.3% ,min $5
4.investing $1000-$5000 per month
Use standard chartered,@0.2, min 10

For monthly purchase of A35, there are only two options, standard chartered and posb

1.below 1k,use posb invest saver
2.above 1k,use standard chartered @0.2%,min $10

you can also read more about my posb invest saver updates at my blog :https://sonicericsg.blogspot.com/2019/03/post-8...

or if you need a guide on how to set up posb invest saver:https://sonicericsg.blogspot.com/2019/03/post-8...

that say if you are looking brokerage ,you could try fsmone which is the cheapest borkerage in sg at a rate 0.008% or min $10