The special cell in Mumbai’s Arthur Road jail, where Qasab is lodged, cost the state $1m to construct.
And another $2m was spent on security. The total does not include legal fees.
Qasab was sentenced to death after a trial in May last year. His appeal is pending in the Supreme Court.
The Mumbai attack claimed 165 lives. Nine gunmen were also killed.
Qasab was found guilty of waging war against India, multiple murder and conspiracy.
Qasab and an accomplice carried out the assault on the station, killing 52 people.
India blamed Pakistan-based militant group Lashkar-e-Taiba for the attacks.
After initial denials, Pakistan acknowledged that the assault had been partially planned on its territory and that Qasab was a Pakistani citizen