I think $100 over the Moto DROID is a safe bet (wherever the Moto DROID happens to be priced at). I don't think VZW will have a problem with mass returns because the estimated 300,000 Moto DROIDs that will be purchased by then were mostly people who watched the DROID commercials and other marketing or went into the store and saw attention drawn to it. They are not the people like us who check daily for information on new phone tech. So, as long as VZW doesn't have an equally large marketing campaign for the Passion and say it's better the DROID, there should be no return worries. Given the almost zero marketing of the Eris I think it's pretty clear there will be minimal Passion hub bub.
About the HD2 price, keep in mind T-mob (Uk) is somehow offering the $899 device for FREE with 2 year contract. Crazy huh?