If you're not overclocking, you don't even need a K series CPU. But people tend to buy components that will secure them from future upgrades. If you're willing to save money you should stick with AMDs which are also reliable for very little cash. Good luck!
If you are in low budget better go with FX 8320 or 8350. It has the same preformance in the games as the i5 or i7, also it has 8 cores, which makes him better, because the newer games are starting to use more cores/threads. Also then u can get this MOBO http://www.amazon.com/ASUS-SABERTOOTH-990FX-R2-0-Mother... .