Funny I found this thread, as I was recently wondering the same thing. The SK sets are EXPENSIVE, especially since I read they are hit or miss.
However, looking on Amazon, I did find this interesting link:
http://www.amazon.com/dp/B00PCHEL7O/?tag=atomicindus08-20
Just in case the pic changes or the product moves, here it is.
If it really was a case of buying 19763 kit ($226 alone on Amazon) and getting the 89039 kit for free ($198 on Amazon) then it'd be a pretty damn good deal at $287 shipped.
HOWEVER there is no mention of the free set in the product name, description, or anywhere else.