Larger companies sometimes sanction obsolete-equipment sales for employees and for the public. Here is an opportunity to negotiate price. Used computer stores have appropriate equipment. They tend to be expensive, but it's worth a try. Department stores, OfficeMax, etc., periodically need to clear out unused obsolete models and display equipment.
Deals abound for leftovers.
If the graphics card is acceptable, this is everything needed. The Internet offers resources for new equipment. These guys pick up retailers' and manufacturers' surplus equipment for a song and try to unload it quickly for a profit. You'll need to add a monitor. This will pop up a list of systems such as IBM Aptiva, Compaq Presario, HP Vectra, and others.