Clearly this is an older question. But it remains a good question. And I'm sure it is on the minds of many current buyers in this rapidly-changing marketplace.
Right now, the answer may depend on exactly where you want to purchase.
Currently, new construction in Boulder city is very limited. The city is landlocked by choice, and building permits for new subdivisions are hard to get. On the other hand, inventory of existing homes is low also, making them difficult to find and purchase. There is much competition for these homes and they often sell well above the asking price. I recently published a post outlining some of the issues at the link below. There is a third option. One could purchase an existing lot on which a home of one's own design could be built. Be careful with this. Boulder's building code is quite restrictive. You will need to do a lot of research before settling on this option.
It you will live elsewhere in Boulder County, you will have more options for buying a new home. There is considerably more construction going on in places like Louisville, Lafayette, , Erie, Longmont and Superior. Like Boulder city, these areas also have shortages of existing homes for sale. So, building in a new subdivision can be more attractive. Often buyers spend long periods searching for an existing home when they could be picking out the finishes for new construction, which makes new construction a lot more appealing for some.
Do let me suggest that you hire a real estate agent if you will buy new. Many new home buyers think they can skip this step. In fact, professional representation often is more important when dealing with companies that negotiate deals on a daily basis. Additionally, real estate agents can give you an idea about the best builders to work with, they can advise you about finishes that might help you sell for the most money a few years down the road and they can give you an idea about what your home will probably be worth after the builder leaves the subdivision. And reputable builders will not raise prices just because you are using a real estate agent. They value the business real estate agents bring them.
Hi Pallenco: Boulder has some pretty serious green building regulations in place that may not have existed when the house was built. A good place to get advice is the Colorado Green Building Guild, which was founded and continues to be located in Boulder. The link below takes you to a page that will help you find professionals with the answers you need.
Prudential Real Estate of the Rockies