Is the price of an unbuilt home negotiable?

I am looking to buy a new home sometime between next spring and a few years from now and I am wondering if the prices of a home built from a plan is negotiable, I have been looking at the prices of many different home builders and it seems that some builders have a much higher cost for a similar home in the same area. I am just wondering how negotiable these prices are, I know that buying a home that someone already lives in is quite negotiable but how negotiable is it with a new house? This will be my first home. Is there any ballpark percentage range that could be a decent rule of thumb as to what can be expected?