Locate two, low-cost two-drawer filing cabinets at a local thrift or discount store to use as a the base for your desk.
Lay newspaper underneath the filing cabinets to protect your floor. Then spray paint both filing cabinets in your desired color using two thin coats of spray paint. For a more vibrant or rich color, use more coats of paint.
Place a low-cost luann door on top of both file cabinets for a large work surface, leaving enough space between the cabinets to pull up a chair. Place the hole for the door knob toward the back of the desk and use it to route computer and printer wires down through the desk to a power source.