If you are tight on money and don't have good parts i.e. power supply or GPU then use that $30 towards that..
usually as mentioned these two CPUs are 60-100$ apart that's what leads to hesitation when building new computer... But for $30 I would get the i7...
however,,, if you are certain you are only using the cpu for gaming and nothing else then... either is fine.
as said in many threads, no difference will be noticed in gaming between i5 and i7