Alex, nubie already made a parts list with approximate pricing.
The parts list goes as follows:
usb hub $10
usb port (add your own hub) $1.50
e810 cable $5-$7
usb filter chip $.80
battery holder $1.50
Jacks (s-video, rca, 3.5 audio) $1.50
custom enclosure ~$8
This right here adds up to $29.80...