RefurBees offers the refurbished HP Compaq Pro 6305 AMD A4 3.4GHz Small Form Factor Desktop PC for $199. Coupon code "HP14" drops it to $149. With free shipping, that's $50 off and the lowest total price we could find. Features include an AMD A4 5300B 3.4GHz dual-core processor, 8GB RAM, 500GB hard drive, DVD drive, Gigabit Ethernet, and Windows 7 Pro 64-Bit.
A 90-day warranty applies, but it's unclear who backs it.