The BBC's operating expenditure was £4.26 bn in 2009/10, while BSkyB's was £5.9 bn.
But I was speculating about funding last week, too, so I idly looked up News Corp vs some other spies.
in the last financial year, News Corp's revenue was about $32.55 bn = £20.45 bn
and it made a gross profit of $11.88 bn = £7.46 bn.
For the same year, MI5's budget was £2 bn.
Couldn't find figures for just News Int rather than the multinational News Corp, but it's all Daddy Murdoch's fiefdom and does give the scale of their relative resources...
Probably takes MI5 longer to get phone & bank records, too - all that bloody paperwork. 