Behringer UCA202 U-Control Audio Interface for $27.76

The UCA202 provides two analog mono inputs and outputs (for monitoring), USB connectivity and an additional S/PDIF optical output for direct analog-to-digital conversion. The stereo headphone output features a dedicated level control and lets you listen to both the input and output. For a fraction of the cost of many USB audio interfaces, you can have state-of-the-art digital conversion, world-class recording and editing software, and hassle-free connectivity between your PC or Mac Computer and any piece of audio equipment.