Probably not hat much off, unless you're talknig about a block of wood, a set of RCA jacks, the dock connrector, a button and some wire, which still wouldn't be that much off. You'd still be ahead getting your own parts and just building it yourself from the ground up.
And yes he's stated that the ballpark price is starting around $550 .
http://www.head-fi.org/forums/showpost.php?p=3172929&postcount=25