Not sure I 'agree' with the chosen best answer.
Honestly I think that it would be better for you to go on us/can sites and even if you pay shipping the currency flips in your favor.
Start off with a good case, for air there's no better than a raven 3.
http://www.directcanada.com/products/?sku=16950AC0512&vpn=RV03B-WA&manufacture=Silverstone%20Technology
It's 130 but comes with enough fans to start (just trust me).
PSU you want a good one, google for the tiers and try to get as high up as possible. I'd say 600+w just to be future-proof. I'm personally running an ultra 850w in one, and a cm elite 750 w in another almost a year on, and no problems.
For a cooler, grab the hyper 212+ even if you go over budget it's 20 bucks and a lot better than stock amd or intel.
http://www.directcanada.com/products/?sku=11130AC8843&vpn=RR-B10-212P-G1&manufacture=COOLERMASTER
Mother-board, honestly it really depends. From personal experience for over-clocking today you don't 'need' a 150 dollar mobo but don't get a $30 one either.
This all depends on what cpu you want; if you want a 2500k, grab
either one
http://www.directcanada.com/products/?sku=11830BD1817&vpn=GA-Z68X-UD3H-B3&manufacture=GIGABYTE
http://www.directcanada.com/products/?sku=16950BD5990&vpn=GA-Z77-D3H&manufacture=GIGABYTE
AMD, I wouldn't go for an 8-core per se. Depending on your res, just grabbing a 3core phenom 2 and unlocking will be more than enough. They won't run at 4+ghz like the 2500k but if you're on a budget it'll allow more room for the gfx. I have a phenom 2 black edition (forget name) ocd from 2.7ghz 3 core to 3.3ghz 4 core on a asus m5 or m7 something (real cheap), and a 2500k ocd on a gigabyte p67a-ud4-b3 to 4.3ghz.
For ram, now-days just go for the 8gigs that are 1600mhz for 30-40 you're better off having more money in your pocket honestly. If you really want (I just might do this). Grab 16gigs.
So far you're probably at either 250-325 for amd and 350-400 for intel. After this, go anywhere grab an ssd 60-100gb I'd rec. and a regular hdd maybe 2 for raid 0 and 1 more for backup if you want. Refurb. drives work well enough and I'd say you can get all 4 hdds for under 150. Otherwise a 60gb ssd off e-bay or somewhere for 60gb and a nice reg. 7200rpm let's say 500-1tb can be had cheap too.
I've seen places like staples offer 1tb externals for $15. There's deal out there I'd expect that to eat up abou $125.
Now, you have a few hundred left over for a gpu, and extra cooling.
Going with the raven 3, I'd honestly rec. filling up all the remaining slots with fans. It''s cost about 30-40 extra but it's the best aircooling money can buy (atm). That's 11 fans in total, 3 in the case + 1 on the heatsink + all the extra slots.
For gpus, for lower res go with an nvidia. If you have enough grab the gtx 670, or the 7950. 7870 with good cooling to oc it will also do very well.
Triple monitor etc. grab a 7970.
If you want to save money, money though; I've seen almost new gtx 580's for $180 on e-bay and a lot of them are probably under warranty too. So that's a good bet, the 580 depite being a bit old now, will still hold it's own at 1080p on most any game going forward atleast until the new console gen (1-2 years). Don't quote me on that though.
If you want to use all the budget though, I'd rec. atleast the 7950, and going forward it seems that as games use more 64bit math AMD will pull into the lead, since Nvidia cards are only optimized for 32 bit (the new 600 series has 3-4xless 64bit pros. power than even teh 500!).
The post may seem to ramble, but take it more as a guide rather than a strict build. You know how much room, you have; what your needs are (more cpu or gpu games), etc. I'm here to tell you, cpu doesn't matter as much, if you want to 'future-proof' sure blow a couple hundred more on the cpu now, but telling you from experience you'll probably wish you chose a dif. cpu and spent more on graphics a year or two down the line.
Cpus have very good longevity especially when over-clocking comes into the mix. I wouldn't worry too much about it
Either of those would work fine for gaming, but if you really want a 2500k it's 220 on newegg, and probably around the same on directcanada.
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103727
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103996
I'd want the top one, but it runs hotter so unless you have a mobo that can handle the wattage skip it. Second one is fine too, clock speed it alright.
Honestly, look at it this way; you're probably spending a good 1-200 more on the intel. Sure it's 'better' now but with a worse gfx card you won't notice. Also, I've noticed AMD supports sockets longer, in a few years anything will be better than what's out now.
You have the option to drop in a brand new proc. into something old with AMD, I doubt that with Intel.
I've build 4 systems so far, two intel, and two amd. All nvidia cards so far
🙂( I know).
A core 2 duo e6600 which was a carry-over from a dell, an athlon x2 black edition (don't recall number),
2500k, and the triple core.
I honestly wish I'd gotten a amd proc. on the 2500k and put a few hundred more to the gfx. The 560 ti I have is showing its age.
Choice is yours,