If you're sticking with an intel build go with the I5's mentioned. AMD build I'd go with the 965BE or 1090T BE. BE=Black edition= Easy Overclocking like the K's for intel. Obviously if you already have an intel MOBO get one of the previously mentioned I5 chips.
1090T/1100T are long gone. You'd only find one used. And the 965BE (or other AMD quads) is more on par (and price) with the Core i3 chips in terms of gaming performance down at the $100-125 end of the spectrum.