Not sure how it works in California, but here in New York we joined with other owners in our newly renovated building 4-5 years ago, hired an attorney (paid by the hour, NOT on contingency basis), and brought in the state attorney general’s office (guy by the name of Spitzer, you might have heard of him…) when the developer failed to deliver what was promised in the prospectus.
It took almost 3 years, but the developer finally agreed to build / repair certain key items and pay a cash settlement in 2 installments once the AG’s office threatened to sue (the AG, bless his whoremongering soul, has a pretty good record in the courts here). I am not sure whether this approach would work with a home not sold via prospectus.
Over the course of those 3 years, while we were battling a very unresponsive developer, the Board at our building spent I believe $75-90K in legal and engineering fees…most of which were effectively paid by the developer in the end.
It was an unpleasant and lengthy battle, but in the end it worked out quite well.