There is no hard and fast rule with New home builders what you need to do is make sure you bring your agent with you on your first visit when you sign in. This is because they generally won't let an agent represent you or help you negotiate a great deal if you already signed in. Another thing sometimes you can not only get a discounted price, but I've also gotten my buyers Free upgrades on there purchase.
I have assisted several buyers to purchase new homes and in each one we negotiated for something different.
If you need assistance with your purchase I have the experience you may be looking for, just email me at firstname.lastname@example.org or call me at 408-705-6578. You can check me out on my web site at http://www.homesbyallyson.com and if you would like to search for properties it is FREE!!
Check out my website and email me if you are in the market to purchase.