First, what's your budget? What's its intended purpose? What do you use it for? What games do you play? What sort of resolution are you playing at? When do you need to uppgrade?
Second, as far as generally speaking, every time you want to upgrade your processor, you'll have to upgrade your motherboard, because the socket is incompatible and its features are outdated.
Third, generally speaking as a whole build (including case, HDD, etc), and building computers from the USA, Intel builds start to shine above $800 USD.
Fourth, check out
http://www.logicalincrements.com/ and
http://www.pcpartpicker.com for inspiration.
For a general gaming rig, say an i5 Haswell + 8GB ram + Nvidia 760/770 or ATI R9280x would be adequate.