Looking for Advice for home building in the Seattle area

I understand the first response might be "don't," but I wanted to lay out some questions. My mom owns a decent-sized lot in Kirkland (she is disabled and bought the property in the 80s). Normally, I wouldn't be able to buy a home in Kirkland, but we've been considering subdividing the lot and building. The city confirmed the lot is fully capable of being split and housing a sizable home, but the cost is a significant concern.

We hope to have a home of at least 2200 square feet with a bedroom and attached bathroom on the first floor, in addition to a master bedroom on the second floor. This is because, at some point, I will need to move my mother from her existing home on the lot into the new house, as she is disabled and will have increasing difficulty taking care of herself.

One of the challenges we've faced is finding builders interested in constructing individual homes that aren't in the 2-3 million dollar range. When we have spoken to people, we get giant ranges for cost per square foot. Does anyone have any general advice for this area or recommendations for builders? I'm not looking for extremely high-end, but I would like a good home for my wife and me to start a family and grow into.

Any help is appreciated.