Hey ControlFreak, i work for a construction company and the way it works for us is payment in 6 stages, 5% Deposit, 10% Base Stage, 15% Frame Stage, 35% Frame Stage, 20% Fixing Stage, 15% Practical Completion. Your bank will go out at every stage to ensure the work has been done. Any variations you do throughout a job often incurr a Variation fee plus the cost of changing whatever you changed, that money can either be claimed at the end of the job or at the appropriate stage of the job.

A lot of builders give a base price which seems cheap but as you say it doesnt include fixtures, fittings, floor coverings. Sloping blocks can be quite expensive.

We have a standard Specification which is included in all our houses then you can add or subtract anything you like, our extras list is

Draws and Glass fronts to kitchen
Glass splashback as per display
Microwave with trim kit
Main floor tiles as display (supply and lay)
Rectified wet area tiles as display (supply and lay)
Glass feature tiles as display (supply and lay)
Feature shower bases
Carpets as per display (supply and lay)
Tiling to front porch & rear patio and around pool (Supply and lay)
Glass wardrobe doors to Bed 2, 3 as per display
Intercom as display
Security System as per display
Ducted Vacuum as per display
Light Fitting as per display
Fans as per display
Split system Air conditioners as per display
TV Antenna with booster
Letterbox Rendered (800 x 600)
Wall mounted clothesline
Pool as per display including sandstone edge
Pool fencing to owners requirements
Exposed aggregate drive way and laundry pad-as display
Drive way sealing
BBQ Cabinet & BBQ
Designer Flake to Garage floor
Metallic Paint on Feature wall
Water tank to owner?s requirements
- 5000L Above-ground
- 5000L Under-ground
Fencing to owners requirements
Landscaping to owners requirements

Some of those items are just upgrades of already included stuff but thought it may help. Also window furnishings like blinds are extras.

Hope this has been of some help if you have any questions PM me, if im unsure there will be someone in the office i can ask, goodluck!!