It is usually better to have your own buyer's agent. In real estate, there are two types of relationships: customers and clients. An agent works with a customer and for a client. A buyer's agent then would have you as a client. What that means is his/her fiduciary relationship is with you: He/she will protect your interests, negotiate on your behalf, give you his/her loyalty, care and confidentiality. A true buyer's agent will protect you and explain to you things that the average lay person does not understand. Toll Brothers is very pro Realtor, but the bottom line is they work for Toll Bros., not you. If I can be of further help, please don't hesitate to contact me. Thanks. email@example.com
The longer answer is that it depends on what type of unit you are interested in and how fast you can move. Builders want to sell their existing inventory before they start to build more homes. The ones that are up and ready will likely be the better deal, assuming it meets all your needs.
TB does cooperate with the broker community and encourages us to bring buyers through. What this means for you is that you can have representation assisting you with negotiations, etc... and TB will pay the commission. We get several emails a week from them advertising the latest incentives.
If you are interested further, feel free to contact me directly.
All the best....