But, selling new, the buyers gobbled up the homes highest in elevation first paying the highest lot premium. This made it easy to support the values of the lower elevation homes even when, as is typical, the builder raised the prices with each new phase. He was smart. If he had built the lower elevation homes first, supporting the higher elevation home prices would have been impossible. It's called marketing strategy.
Upgrades are also difficult to appraise in a manner that supports the increase prices.
Technically speaking, more upgrades could be construed in terms of a higher quality home. However, the underwriter will not accept a variation in quality in the same tract. So, you create a separate adjustment grid for upgrades. I usually put upgrades directly under the basement column. I explain in the report why I do it that way in liew of a quality adjustment that can be very subjective.