I have a super stable connection right here in Germany, and no, I am not playing overseas I am just logged into the us-battlenet (playing in the EU) because everythings closer to the devs in here. 10-30ms is my usual ping. Always.
So either fix the connection issues - I am speaking of a 300-2800ms Ping! which makes the game unplayable - or give us an offline feature (for example with not accessible-RMAH!)