Cost of Administering the US Income Tax

[KUJustin]

Without turning this into a debate on the merits of said income tax, can anyone here give me some direction on finding out the total cost of administering it? I'm coming up short on Google.

This would include the total IRS budget, but also all the money spent by private firms and individuals in terms of internal man-hours, accountants, forms, etc.

FWIW (nothing), my out-of-thin-air guess is $200B annually.