I thought you were already crazy for bothering to use the vortec efi on an L28, then using exactly none of those savings to spend on something better than a chinese ebay turbo, but this definitely takes the cake.
Good quality LS heads aren't even under $1000, unless you're getting something totally bare with no springs or valves, and that's a product for the most widely produced engines in existence and required no custom engineering.
I don't think you have any idea how much time and money it costs to create something like this for an already very niche market. What you might be thinking of as a "real head manufacturer" would never bother doing something like this head because the market and sales would never justify committing resources to it, and if Derek created licensing for someone to mass produce it now that the hardest part of the work is done he'd probably get paid pennies for the amount of time it took to develop it.