I wish more high schools had them. Building one from the ground up is even more. That brings the price up. But because of the low maintenance, the long term cost is less. If you love the idea of a sport court surface, but can't stomach the price tag just for a tennis court, you might want to consider using it for other things.
Combo courts are the hot trend.
Terrian agreed that combo courts are good for a lot of people. Besides net sports, a combo court can be used for other popular activities like rollerblading. The sport court surface can even be frozen in the winter for ice skating. Of course, the court surface isn't all you need. Nets, net poles and perhaps even soft netting or a chain link fence around the outside of the court need to be figured into the cost.