"U.S. foster adoption is the least expensive adoption route, by a significant margin, with an average cost of less than $5,000."

They don't clarify how much less, but plenty of other sources put the average below $3000, and with tax credits it's certainly net profit.

Private adoption is the equivalent of buying a pet from a classified ad. Buy from the pound instead, you'll be doing a greater public service and get just as much out of it.