$25 per imp card plus the cost of imp-ized devices to hold them. I'm trying to comprehend the cost of doing every light switch in the house. It would get pricey. Consider what I've done now, the $40 "solar timer" switches I put into two sockets to control lights that I want to turn on automatically at night. What would an imp-ready light switch cost, such that I could program it to behave equivalently?