My son worked at a major studio in LA for a year or so. I believe he said that studio costs alone were $4 grand a day. And some artists were there literally for months. And that doesn't include producer's fee, equipment rental, tape, food, booze, hookers, etc.

Of course this was well established, top of the line, fully staffed and open 24x7x365. Not your local garage bands recording their first cd but folks with big record company money behind them. Whether it's worth it or not is another question, but it's easy to see how recording costs can get up in the millions.....