Cheap desktop computers?

Does anyone know of a site where I can purchase cheap desktop computers that will ship to Canada? They do not have to be new models. Perhaps some refurbished ones. I don’t need monitors or keyboards or anything else either. Just looking to replace some hardware for my office. Thanks in advance!

A few options that I’m aware of:,,

If all goes well in the new year then sometime in late January 2012 the Raspberry Pi
PC package goes on sale for around $35, no idea about shipping costs though. Should be ideal for the
average home or office desktop role.

Target price: Model A US$25 (GBP £16) | Model B US$35 (GBP £22)
SoC: Broadcom BCM2835 (CPU + GPU + DSP + SDRAM)
CPU: 700 MHz ARM11
GPU: Broadcom VideoCore IV, OpenGL ES 2.0, 1080p30 H.264 high-profile decode
Memory (SDRAM): 128 MiB or 256 MiB
USB 2.0 ports: 1 on the ‘A’ model and 2 on the ‘B’ model (via integrated USB hub)
Video outputs: Composite RCA, HDMI
Audio outputs: 3.5 mm jack, HDMI
Onboard storage: SD / MMC / SDIO card slot
Onboard network: None 10/100 wired Ethernet (RJ45)
Low-level peripherals: GPIO pins, SPI, I²C, UART[23]
Real-time clock: None
Power ratings: 500 mA, (2.5 Watt) [1] 700 mA, (3.5 Watt)
Power source: 5 V via Micro USB or GPIO header
Size: 85.60mm × 53.98mm(3.370 × 2.125 inch)
Supported operating systems: Debian GNU/Linux, Fedora, Arch Linux
Unsupported operating systems: RISC OS (shared source)