Don't change your plans. The cinder block is a excellent means of forming foundation walls without pouring concrete and making forms. Hands down cinder block is better. For one reason there is an air gap between the ribs of each block. This serves as a natural capillary break, hence discouraging water influx. This could mean a lot if you are considering the cost of heating a basement or crawl space. Thus cinder block offers reduced conductivite with outragious opportunities to enhance the insulatings properties of the foundation wall. The cost of the cinder block will vary with the region and availibility. The costs of concrete per yard including form work is typically more expensive. Factor in contractor labor and large square footage dreams are immediately disouraged.