How do you make a splash in the heavily entrenched U.S. and U.K. mobile markets, which are dominated by Android and iOS? Release a Firefox OS-based device for just $79.99 off-contract and unlocked, that’s how. Want to raise even more eyebrows? Offer it exclusively via eBay. That’s exactly what ZTE is doing with the Firefox mobile platform-powered Open “soon,” with orders apparently opening Friday.