GamerBoy357 :
firstly, the i5 6500 is cheaper than the unlocked i5-6600k
secondly, an i5-6500 overclocked to 4.5 GHz can produce better results than a fully unlocked i5-6600k when paired up with faster DDR4 RAM.
source:http://www.eurogamer.net/articles/digitalfoundry-2016-intel-skylake-core-i5-6500-review
1. The price wasn't the question
2. That was one test, the article is from January, it hasn't proven consistent. And that ability has since been locked out.