Lifts would still add a significant cost compared to a station without no lifts, a station with no lifts has no moving parts, and only needs electricity to run the lights, opal readers, and PA system.

Lets look at the most recent lines built, where stations are (in bold) and where they should also be (in normal text) but with less extravagant stations i.e: no lifts):

EAST HILLS TO GLENFIELD: East Hills, Voyager Point, Holsworthy, Wattle Grove, Glenfield
SOUTH WEST RAIL LINE: Glenfield, Bardia, Edmondson Park, Edmondson Park West, Leppington East, Leppington
NORTH WEST METRO: Epping, West Pennant Hills, Castle Hill East, Castle Hill, Showground, Norwest, Bella Vista, Parklea, Kellyville, Beaumont Hills, Rouse Hill, Tallawong

Some of these stations might get less patronage than the existing ones, and the costs of lifts might discourage their construction, but their construction would reduce car depending and discourage urban sprawl.

I'm not saying these stations should NEVER have lifts, but rather they should be opened without lifts and have the lifts added when the demand and need is there.

What a load of crap. No cheap and nasties should ever be built. New stations need to be fully compliant and to say otherwise is just discrimination against the disabled. Putting stations so close to one another is no good unless you are running metro rolling stock which is the reason why these stations don't exist but lets look at some of the stations you mentioned.

Voyager point - This suburb literally came in to existence the year the east hills line was extended to Holsworthy and it wasn't planned. Do you really think they didn't build a station here because they had to include lifts.

Wattle Grove - I agree this station should exist but if you think it doesn't exist because of lifts increasing the cost of the station you are mistaken. This has more to do with the position of the station and the proximity to houses. I also think this has more to do with no room for a car park then anything to do with lifts. I have no issues with a station that has no significant car park.

Bardia. - This just shows you how prejudiced you are against the disabled. This station would still require a concourse over the rail line somewhere and it is a ridiculously short distance to Edmondson Park station. You could do more for the people of Bardia by putting in a foot / bike path so they could walk or ride to Edmondson park.

Cowpasture Road - This would be the place to put a station between Edmondson Park and Leppington. There is no way Jose that you could build a station here without having a lift as it would act as a bus interchange and to not include a lift would be borderline criminal.

West Pennant Hills - This station would require Lifts for it to even be possible to exist because the train line is so deep at this point.

All the other proposed NW stations - Your argument is mute on this because any station is going to be either underground or above ground making these stations expensive regardless of if you include a lift or not. Parklea already has the Tway doing what you propose and Beaumont hills isn't even on the rail line and it is also on the tway.

Point taken regarding metro stations and Cowpasture Rd, as for Voyage Point, if the suburb came after, add the station then, I have heard it argued though that it would serve few people (but even 100 people a day would take strain off Holsworthy), it could be possible to create a business case for a small basic unmanned station (like Casula), add in the lifts and then cost may be up for debate.

Please remember personally, I also want every station to have a lift, but if that means a car is required to use public transport then that leads to this discussion.