Buy a new Townhome in Fullerton/Buena Park, CA?

New constructed community. The TH is around 1500sqft, 3 br, 2.5bath, ask for $540,000 (basic price). Is this a reasonable price? or how much should be reasonable?

Also when buying a new TH in CA, how can I negotiate with the builder?

Please kindly share your advice! Thanks!