just returned from a batam trip with my first KTV experience. Spend around 150-200sgd per person including the girl sit-down fees. SYT 22 yo only.
GFE was good and after the night, girl just followed me back to hotel without any mentioning of fees or money (

dont know how this works) and we did the deeds then cuddle to sleep. Woke up and passed her something like 1.5mil for tips and transport, no objection from her.
YMMV, had similar experience in another country 'JTV' bar.