First we head to AnandTech, they conclude the Core i7-875K hits the mark on price, it's kinda weird bit with a price tag of $342 this unlocked chip is significantly cheaper than the Core i7-870 which has the same specifications, yet commands a $562 price tag. The site also points out that these chips aren't targeted at die-hard overclockers:
Our perceptions changed when Intel told us that they will not be binning these processors in a special way or marketing them at die-hard overclockers, but instead at system builders who can utilize the unlocked core features to provide cheap pre-overclocked systems with minimal fuss. In the same vein, the K-series will allow users to purchase cheap motherboards that don’t need overly complex BIOS options as we only need control of core multiplier ratios and VCore to get a quick and easy overclock. Bearing these aspects in mind, it’s hard for us to be negative about this launch; however, we’d like to see Intel unlock more processors in the future.Another review can be read at HotHardware, they conclude the Core i7-875K is a relatively affordable processor, but that the Core i5-655K isn't really worth the $40 premium over the i5-650.
The unlocked Core i5-655K will command a $40 price premium over the locked i5-650, which is a bit steep in our opinion, but at under $220 it is still a relatively affordable processor and offers much more flexibility while overclocking than the standard i5-650. The Core i7-875K, despite having an obviously higher price, is priced to move. You're reading the chart correctly--the Core i7-875K will sell for $342, which makes it almost $240 cheaper than the locked Core i7 870. Intel will have to adjust pricing on the 870 eventually, but when it initially arrives the Core i7-875K will be much more affordable than 870. If you've been contemplating the purchase of a Lynnfield-based rig for overclocking, and have the budget to afford the 875K, it is absolutely the processor to get. Flexibility, performance, and competitive pricing--the Core i7-875K has it all.Last but not least, a third in-depth review can be read over at The Tech Report.
Like I said, it's good to be king. Intel has calibrated its response to the Phenom II X6 quite carefully, and the result is a clean sweep. At stock clock speeds, the Core i7-875K is a better performer than the Phenom II X6 1090T—just a little bit in multithreaded applications, but quite a lot in single-threaded ones. The 875K is also a (very slightly) better value. When both CPUs are overclocked, the 875K retains its performance lead. Either way, the 875K is more power efficient than the 1090T, too.