Larry my man, I go to your posts when i'm looking for cheap replacements for relatives PCs. However, I think that for what you are truly looking for, it makes a lot more sense to go for the second from the top. For example, in sandy bridge time, 2600k instead of 2700k. Now maybe the 4790k instead of 6700k (budget depending of course, and whether or not it makes sense, do you have a micro-center, etc).
I do not think it makes sense for a main usage PC to go budget with the intent of buying every couple of years to replace. I bought my 2700k PC parts going on 5 years ago. @ 4.6Ghz, the then halo part is still competitive. Will a 6700k beat it? Obviously. Would it be worth it for me to switch however? Probably not. I have mine undervolted as it is, and only REAL gains I would get are via chipset, but I single card game only.
People who got their x58 platforms coming up on SEVEN years ago, are still often times doing fine, and depending on what they do, not looking for or needing an upgrade anytime soon. Can you say that about buying the Pentiums, celerons, or i3's of the same era? Probably not. I truly believe that you save money by getting the high end (but not the highest!).
I think you should buy for what you need. If you need an office PC, get an i3 with 8gb. If you are getting a gaming / photoshop / workstation / high usage power needed, get an i7 4790k, 5820k, 6700k, depending on your needs, and you will be good for quite some time. (As it stands, according to current pace, upwards of 5 years).
Video cards on the other hand you can often skimp out on, as buying the mid tier usually loses you 10-20%, at a 50%+ reduction in cost. That I can live with a more frequent upgrade cycle.