Low-power processors often command a sizeable premium over their vanilla counterparts, but it doesn't always have to be so. For instance, Newegg is running a promotion whereby you can get AMD's Phenom II X3 705e processor for just $109 with free shipping.
This CPU normally costs $124, but entering the promo code "EMCLVNP39" on the shopping cart page lets you get it down to $109.
Admittedly, the 705e lies in a crowded playing field. You can get the slightly faster Phenom II X3 710 for just $99 shipped or the faster-yet Phenom II X3 720 Black Edition (which has an unlocked upper multiplier to boot) for $119 shipped. That said, the 705e's thermal envelope is a whole 30W lower than the others (65W instead of 95W), so it should be a much better fit for quiet or small-form-factor systems. Also, parts tuned for low power consumption often have good overclocking potential. That's worth keeping in mind.