Although this is an old thread, but you can try try this:
https://www.theaudioboard.com/
After you register, and save your searches, you will get instant alert once something comes up that matches you searches.
Search by zip code issue
For the past 3 weeks or so no new listings appear when doing a search by zip code. The listings that appear today have 8 days or less to expiration. I prefer to purchase locally and use the feature regularly. I've emailed Audiogon support twice with no response. Anyone else having this problem?