PCGH.de made a quick review of the Phenom X4 9100e, the first energy efficient quadcore processor from AMD with 65 watts TDP. It comes with 1.8 ghz and B2 stepping.
Cheapest quadcore you could find for desktop, runs at 1,8GHz. AMD Phenom X4 9500 is being sold as low as 110€, the 9100 will easily go sub 100€.
On the other hand, it is beaten by dual core Intel E8500 in nearly all tests. I wonder what overclocking headroom there is to be found in these, if they can reach 2,6GHz (which is no problem for the 9850) consider yourself having a überfast quad core computer at low-end price. Intel doesn't offer cheap quads and sub-100€ best I could find was E4600 (2,4GHz; 200MHz FSB). The E4600 will never overclock high enough to compete with the 9100 running at 2,6GHz, in multithreaded apps that is. Very interesting offerings from AMD.