From what I read, extracting Saudi oil is very inexpensive around $9 per barrel with only $3 of that the marginal costs of pumping the oil. As a comparison, Canadian oil costs $26 per barrel to extract from the oil sands. Whether that translates to a 35% net profit margin I do not know.
Yeah, just pondering it now. Not only are they in a very fortunate position, as far a oil extraction goes, they probably have no minimum wage, no unions, no environmental regulations, no zoning problems... Not to mention they are part of a cartel. Hell, anyone could make 35% under those circumstances.
The price at the wellhead for the Saudis hasn't budged much in straight dollars (was about $8 in 1973, prior to the embargo), and that's not taking inflation into account -- their cost has actually declined over the last 46 years.