Well, you will get a ton of advice here. First, as others have said, tax (or county) appraisals are not market prices and shouldn't be used to judge on what you are trying to pay for a home. What needs to be used are comparables in the market area you are buying. A comparable is a home, like the one you are trying to buy, that has sold in the past 3 to 6 months.
That being said, if you are trying to buy a brand new home from a builder, they are going to charge you for what they charge other builds in the area. They may not come too far down off of the price that they have given you. You can ask, but depending on the type of home and area, they have some set prices on what they are willing to do. However, they may be willing to throw in extra amenities.
As far as hiring a RealtorÂ®, well, I think that it's always necessary to have one. But, now that you are working with a salesperson at a builder, they may not allow a RealtorÂ® in with the negotiations. Well, let me change that a bit. They will allow one, they many not compensate one at this stage of the game. This means that you may have to pay for one out of pocket or find a RealtorÂ® you can trust and go to another new home community. However, do ask the new home community if they will be willing to compensate your RealtorÂ® because honestly, you should not be without one when trying to buy any home, new or otherwise.
RealtorsÂ® will be able to advise you and make sure that you are getting what you want and your needs are being met. New home sales people are terrific individuals; however, they work for the builder.
Anyway, I hope I have helped. If you are looking for a buyers agent and would like help, please feel free to call me and I will see what I can do. Lots of luck to you.
RealtorÂ®, ABR, e-PRO