Newegg via eBay offers the refurbished HP DC7800 Intel Core 2 Duo 1.83GHz Desktop PC (no monitor) for $119 with free shipping. That's the lowest total price we've seen for any HP DC7800 desktop without rebate hassles. (It's a current price low by $6.) It features an Intel Core 2 Duo E6300 1.83GHz dual-core processor, 2GB RAM, 80GB hard drive, DVD-ROM, and Windows 7 Home Premium 64-bit.
No warranty information is supplied.