I'm seeing the i7 5820k as the cheaper of the two by $18
http://pcpartpicker.com/parts/compare/intel-cpu-bx80648i75820k,intel-cpu-bx80662i76700k/
Sure X99 motherboards are expensive but he chose a $282 Z170 so he could easily spend less on a still great X99 like the $239 X99-A for example.