Would recommend copying your plans and marking out where you want power points, downlights, battens and light switches - makes the appointment easier. Light point gets you wiring and a batten. You pay between $70 and $80 for the downlight or oyster fitting - there are other more expensive fixtures but we didn't go there.
Be aware that you need to pay $256 for an extra power circuit for every 7 extra double power points (14 singles) and an extra $245 for every 20 extra light points. Adds up pretty quickly.
Good luck