That's about £240 per customer. To be honest it would be cheaper to run a decent TV marketing campaign and a special offer "First 3 months free to Tiscali customers". I wonder how much Tiscali's TV campaign cost them. Surely the Sky broadcast network could be employed.
I suspect BSkyB won;t be to bad a home for the poor users, but buying another companies unhappy customer base is a quick fix; and quick fixes always come back to bite you, as Tiscali has already found out.