The next auction (in Germany) for enamel signs on the 10th of November is at:
www.reklame-auktion.de
The descriptions are in German and English. Very good auction. Some nice English enamels also available. You van bid online (first you have to register) or watch the auction live.
The auctioneer speaks good English so dont hesitate to ask any questions. I can help also if needed. Here are some examples: