6600K (assuming you are gaming only - didn't mention uses...)
Z170 based motherboard (any from say $130+ will be fine for overclocking - motherboards do not matter much these days for 'overclocking potential' - go on features, look, and price)
2x8GB DDR4 3000-3200 CL14 (brand doesn't matter much either, ram is ram is ram for those not benchmarking at hwbot). I wouldn't go less than those speeds as its DDR3 speed with DDR4 latency.
As far as the best deal MC has great deals on CPUs, yes... and some motherboards/combos. You will have to do some shopping on your own though for the best deal. PCPartpicker can help you with that.
Good Luck.