That would be per year, not per month. I don't think even the highest paid manager in LA makes $900,000 a year.
$150,000 a year then.
Who have a salary and draw and expenses. And they get a big cut of anything sold. If you sell $1,000,000 in a year, the first $250,000, give or take, goes as sales expense. For example, agency accounts take 15% and the seller likely gets around 5% and other sales expenses like base salary, FICA, gas allowance and insurance are at least another 5%.
Then add in someone for traffic (commercial logs, not honk-honk traffic), accounting, production, chief engineer, operations manager / program director.
Insurance (liability is expensive for a talk format) including fire, theft and others, usage licenses, legal, phones (land and cellular), engineering salaries, engineering & technical parts and supplies, consulting engineer, FCC expenses & license fees, Communications attorney, business' share of Social Security, health insurance for staff, dues (NAB, RAB, SCBA, etc), subscriptions, office supplies, computers and software licenses, gasoline and travel allowances, conventions and meetings, janitorial and trash removal, postage/shipping/delivery costs, auditing at year end, production library, outside voiceovers and production, agency commissions, etc., etc.
Actually, it is not that much as you are projecting monthly salaries that are actually annual ones.
Outside of the lease to the station owner, I'll bet it costs less than $250,000 a month. My guess, again not including the lease, would be in the $175,000 to $200,000 a month range.