If I want to do DCA of $250 each a month on: SDPR Gold Shares O87, STI ETF, VUSD and MSCI World ETFs which broker would have lesser fees?

For SPDR Gold Shares and STI ETF, the cheapest option will be FSMOne's ETF RSP. It is min $1 or 0.08% whichever is higher.

For VUSD, you cannot do so on FSMOne's ETF RSP since it does not support ireland domiciled ETF. The next best alternative will be VOO which is available on FSMOne's ETF RSP.

For MSCI World ETF, you cannot do so on FSMOne's ETF RSP since it is not available on their RSP list. The next best alternative will be VT which is available on FSMOne's ETF RSP.