i7 920 - $ 279 at Newegg though you can do better than this if you hunt around -
http://www.newegg.com/Product/Produc...82E16819115202
X4 955 - $245 at Newegg. Not sure if you can do much better here since the overclockers are all over this CPU. It clocks to nearly 4GHz using the stock cooling that comes with the retail part. Add a custom cooling kit or water cooling to this and the sky's the limit it seems. Some idiot is posting online that he got one of these things running at 7 GHz. I'll have to read that one. I'll post a link to it when I get a second to find it again.
-S