I've built twice, and the 'extras" can be very exxy!!!!

air con
driveway
fencing
turf/gardens
blinds
curtains
carpet/tiles
clothes line
garden shed
window screens ( ive seen these not included before!)
water tank ( complusary in most states now)
mailbox


Also check with your builder about your allowance for each item. They may allow you $20 per door handle, and they could be the most basic ugly ones. Nice ones might cost $35, which is a lot if you have around 7-8 doors!!! And this goes for bricks, tiles, paint, handles, bathroom acc. etc......

HTH......