Using spray foam in a your home's crawl space allows your home to have a more energy efficient way of insulating your home.
Spray foam is a cost efficient way to insulate your home. Though the up front cost may be more expensive than a normal insulation the amount of energy and money it will save will be more cost efficient in the long run.
Many homes with spray foam insulation have warm floors and an all around warmer home. The amount of energy the spray foam insulation will save you means that your home will be warmer.