As a realtor, who has a degree in interior design and has always bought new homes, I would suggest you also consider the following:
1. If the builder completes the upgrades, the work is done prior to you closing and moving into the home. This may more be advantageous than living through the remodeling process to do those upgrades after the fact, which can often drag on for months. They will also be covered under the builder's warranty (usually 1 year after closing) as to workmanship, etc. If you do not have time to shop for the upgrades at numerous retail stores, be available for workmen to come and go from your home, or have the knowledge/expertise to act as your own general contractor, you may find the time you'll need to invest costs more than the money/interest you would have saved.
2. Alternatively, the builder may have limited options available to you. Are they what you want? Are they priced competitively to what you can purchase on a retail basis with the extra labor needed for installation? Do you have a designer you can work with to help with color selection and making sure that your choices are good quality, compatible with what you are trying to accomplish and are aesthetically pleasing?
3. If you are making structural changes, it is much less expensive to have the builder do them at the time of construction. Also, you run less chance of surprises that cause your great idea to now be your worst nightmare. If you are only making cosmetic changes, that may be less of an issue.
4. Don't forget that you often need a permit and to have inspections done to pass the work done. The builder is already aware of those permits and inspections. So unless you want to hire a professional (architects, designers or general contractors) to help you "retrofit" the changes, you might have a lot less brain damage by working with your builder. Don't be afraid to ask if the builder can include certain things, or give you a better deal by working with them.
Enjoy the process. Whichever route you decide to go, it can be exciting to see your dream home take shape. Be sure to be involved in the process from day one and don't hesitate to ask questions, make suggestions and create a great home.
Karen Hermelink, CRS, e-Pro