Amazon offers the Intel Skylake Core i7-6700K 4GHz Quad-Core LGA 1151 Processor for $277.22 with free shipping. That's the best deal we could find by $2, although all other merchants charge $324 or more. (For further comparison, in February we saw it for $17 less, but only via in-store pickup.) It features a 2MB L2 cache and 8MB smart cache.
For in-store pickup only, Fry's offers the AMD Ryzen 5 1400 3.2GHz Quad-Core AM4 Processor for $149.99. That's $19 under our mention from five days ago and the lowest price we could find now by $18. It features a 3.4GHz max turbo frequency, 2MB L2 cache, and 8MB L3 cache.