The Virtuix Omni is an omni-directional treadmill that, when combined with Oculus Rift, aims to offer the most immersive virtual reality gaming experience to date. $500 will snag you one treadmill with special belt, shoes and tracking hardware and software. The "Duel Deluxe" package for $1,020 will net you two treadmills and aforementioned accouterments, plus a third pair of the special shoes. Shipping costs (this thing is heavy) will be incurred when the Virtuix Omni is delivered in March 2014.
When the Virtuix Omni began its Kickstarter pledge drive, the device was only seeking $150,000 - that goal was exceeded in the first day alone. After 30 days, the Virtuix Omni was able to secure over $1.1 million in crowdfunding.