For private both consultations and tests, scan, vaccination are more expensive.
For subsidy, all costs are subsidy thus much cheaper.
Example, private consultation fee will be around $80-150; subsidy only less than $30.
Scan, test and vaccination, works the same.
So if financial is a concern, do go through the subsidy route.
Yes, you need a referral letter from poly. Please make sure you visit the gynae timely, as you need to ensure baby is growing well.
Take care and God bless you and baby.