I agree with ijustluvit that it is less costly to upgrade after the sale and that it is more advantageous in all the ways she mentioned-- more choice in final product, ability to select contractor and negotiate contract, ability to supervise and make adjustments.
I also agree with Bare and I2ride that, when compared correctly, resales are a much better value. We looked at scores of houses before buying in TV; and in apples to apples comparisons (including bond difference and valuing only the upgrades you want) the only resales that were not a far better value than a comparable new were the ones that were overpriced.
In an area that still has new homes for sale, it almost seems inherently true that resales are a better deal. If, in an apples-to-apples comparison, you could get a new one cheaper, why would anybody buy a resale. And if nobody would buy a resale, our homes would have no market value at all. Afterall, you can buy a new home, but you can never sell one. Oh dear, I hope that made sense?