The one thing that really may be hard to get as they are already in limited quantity is the 6950. That is because the new 7xxx series has been released. A 7850 is probably the price you would be looking at and is slightly better performance, uses less power, and is a tiny card.
The cpu is a good call since it is the newer version of the 2500k. You should hopefully be able to find the 2500k still, but if not, the 3570k is close in price and should be good. A cheaper mobo similar to your 2500k one is the asrock z77 extreme4. It actually comes with more goodies than the z68 variant which is nice since it is a similar price.
Beyond that, not much else has changed which is fine since most stuff should still be around. However, the cpu cooler and ram are okay upgrades at best. There are definitely better products for the price. For cpu cooler, the next step up imo would be the thermalright true spirit 120 or 140:
[ame]http://www.amazon.com/Thermalright-100700529-True-Spirit-120/dp/B005MSOH7C/ref=sr_1_5?ie=UTF8&qid=1343588783&sr=8-5&keywords=thermalright+archon[/ame]
[ame]http://www.amazon.com/Spirit-passed-Intels-testing-officially/dp/B00629G1PG/ref=sr_1_4?ie=UTF8&qid=1343588783&sr=8-4&keywords=thermalright+archon[/ame]
I don't suggest wasting money on the v8. It is a decent cooler for the price, but it is overrated.
And for ram, no reason to upgrade to 1866. Stick with the 8gb ddr3 1600 1.5V Cas9. If you did upgrade, get the samsung ram that runo had mentioned:
http://www.newegg.com/Product/Product.aspx?Item=N82E16820147096
Or upgrade to it anyways as it is great ram using low voltage and doesn't require any heatsinks due to the smaller manufacturing size.