I don't think anyone has come out with a cheaper sensor/activation system for SSD. I've seen custom jobs, but none of those for sale, and they're still much bigger than scaley ones. Also, the solenoids and flippers aren't something you can just whip up with some scrap MDF and a magnet. In the end, although it seems expensive, the Scaley lane changers have everything needed at the cheapest price. They're also the most compact.