what does mean : I need cash, IN A BAD WAY thank you.
Desmond says Brian he needs cash in a bad way because he is unable - or unwilling - to be hired for a honest job. So he is doomed to get cash by taking part in that bad band which is living from drug peddling, robberies and whatever. A bad band is not a gang though.
If Melampyre likes non-sense, it doesn't mean it's a bad band. So much the better.
It would be may be "j'ai méchamment besoin d'argent" Wouldn't it?
Indeed: "in a bad way" means "urgently", or "very much".