$799 for just a unit is rediculous. I've done these for years and the kits i've sold ranged from just under 100 to around 500. there are a couple more expensive ones out there with more options, but you can do it much less than 800.
is that $300 price installed from them? if so then that's not bad at all for a dealer piece.
2010 Volvo C70
2011 Harley FLHTK
Midwest Crew #22