Take a look at the Post titled, "Buy through Amazon, unlock through GSMPS": Buy through Amazon, unlock through GSMPS
You may find your answer there. Essentially, people have been purchasing 8700C handhelds through Amazon and canceling their Cingular accounts, within 3 days, as is allowed according to Amazon's agreement. However, the handhelds were not returned, without penalty. Apparntly Amazon's language does not really address this, or if it does, they do not enforce it. Amazon must have finally caught on...