I would say about $20 bucks on ebay, its a little rare as most manuals are VB-VK so that might help it sell for more on ebay.
Dont bother buying one spend a bit extra and buy the genuine GMH VB one usually about $50
Scott
Loads of VB-VK information, All you need to know about EFI 5L Conversions Ultimate EFI 5L Conversion resource "
Wanted B Cast Heads PM for details