Patrick,
Perhaps we have to separate them, but maybe not. I have seen housing project courses with both limited and huge budgets. (of course, the huge budget ones have gone to JN or Faz......) and as someone mentioned, some developers think a huge budget is required for a high end housing course, while others figure the course is a neccessary amenity to be built as cheaply as possible. Sometimes in those cases, the developer figures he will sell it, and often cuts corners that would save maintenance dollars down the road.
In other cases, the eartmving goes up, primarily to sink golf holes 4-10 feet to provide a gentle downhill view from the surrounding lots. In some cases, the golf course dirt is required to build up lots and/or balance the grades with surrounding lots, as opposed to being an internal balance.
But, as to your central theme, every course is different in its requirements, but in general yes, a course pretty much costs the same in irrigaation, full paths, etc. Earthmoving is a big area where you can save money, and a tight budget course usually requires less earthmoving. In my experience, it requires better routing to fit the land to reduce earthmoving. That said, once a routing contains mostly natural golf holes that require little earthmoving to be good (basically building greens, tees and any fw hazards, which takes less than 100,000 CY) some gca's (myself included) then move another 50-75K of earth for what I call discretionary purposes, to valley out fw, build containment mounds, other hazards, etc. And, some move way more!