I managed to successfully sell the old Core i7 4770K via Rakuten Auctions. I have a week to send the CPU to its new owner, but before that I had to buy a new 4790K CPU.
I waited for CPU + motherboard combo deals for weeks. Like I mentioned in the earlier post, Sofmap is selling CPU + motherboard combo for with a JPY5000 discount, but they are not selling any motherboard that I want to buy. If I was going to get a motherboard as well, I wanted it to be a Micro ATX motherboard, which is imperative to my PC shrinking project. As there weren’t any appealing online deals, I decide to finally buy just the CPU and ordered the 4790K in the evening from Amazon. I paid extra for the instant delivery - it's a small sum - so that I could get it one Saturday and play with it over the weekend.
I'm still not sure that I would be getting a good chip. If the past is any indication, it would be a crappy overclocker - I would probably get 4.6GHz at 1.3V. It'll be still better than my old chip and probably will run cooler and use less power.