How do you protect yourself when you plan to build?
We are looking to build a larger home in California and are about to purchase a finished, graded lot to start the project. We have a good idea of what we would like, the level of "upgrades" and the size of the home, etc. We have identified an excellent and experienced architect as well. We know what the lot will cost and have some estimates of the construction cost (and they vary like a ping pong ball's path). We've been doing a ton of research for the last 6 months and are ready to proceed.
My question is this. How do I protect myself from making sure we are not going to be caught in a situation where the cost may be WAAAAY more than what people are telling us? For example, 2 different builders and our architect told us we can "easily" build for $200/sf when I discussed the size of the home, the type of kitchen appliances, granite, fawcet quality, etc we would like.
Then we have spoken to a couple of builders who are like, "it can't be done under $400/sf, those people are crazy, they are lowballing you." My concern is that we buy the lot, design the home, and the people who say it's $400/sf are RIGHT and we are doubling our budget (and hence can't afford to build).
Is there anything more we can do to make sure we are not going to be caught in a situation where we own an empty lot but can't afford to build on it? Of course no one is willing to give us anything in writing till we give them plans, and we can't give plans till we enter escrow, get the detailed lot info, etc.
I am very concerned even though I feel like I have asked a LOT of people about this. It just seems like numbers are ALL over the place!