The court previously heard that the men, two of whom are alleged to have received terror training in Pakistan, planned to detonate a series of suicide bombs in an attack that could have been bigger than the 7 July 2005 atrocities.
The jury heard that Ali registered two accounts on eBay's online charity website "half in jest" in September 2006, with the user names "terrorshop" and "shopterror", using the email address email@example.com.
Brian Altman QC, prosecuting, said that eBay closed down one of the accounts in October 2006.
"The second account remains active, but, like the first, has never been used," he said. "However, both reveal his mindset even then, even if the usernames he chose were registered half in jest."