One of our people answered this question in Oct 2009.

It appears Radio Shack still has them, Catalog #330-0288 - Replacement Headphone Earpads
They can be purchased online here

www.radioshack.com/product/index.jsp?productId=3786220#330-0288

If you can't get them from found some you can look at that are claimed to fit Aiwa on eBay.

90mm-OVAL-Headphone-ear-pads - Measure yours, read their information