BTW, my wife says that using a merino blend fingering yarn only takes about two skeins per major colour (rakers take an insignificant amount). She gets her yarn from KnitPicks and it costs roughly $2.00 per skein.

So, unless they are having the marled yarn custom-made (hard to find in suitable colours)...ie. red and black marling or green and black marling...there isn't that much advantage to the "bonus yarn" offer. Not that it's not a good deal but rather that it probably shouldn't make the difference in whether you see the book as worth having or not.