The Joyport is nothing but a small form-factor PC motherboard (VIA EPIA, actually) in a weird-looking box, running some home-grown Linux "thin media client" software. There is no unique value whatsoever in this hardware - any one of us could build the same box for far less than you're charging. Your entire value proposition therefore lies in the quality & completeness of your software.
Unfortunately - even with great software ( a big IF ), I think you're too far behind the curve on hardware. The EPIA motherboards are woefully underpowered. Assuming Roku ever gets their software complete, I think their HD1000 hardware would wipe the floor with your Joyport for less money.