Keep calm I have a cunning plan

The west seems to be a little unhappy with certain parts of the middle east, one part it certainly isn't unhappy with is Saudi Arabia, Is there any reason why some western governments have a love affair with a country that is well on its way to smashing its own personal best in beheading. The obvious answer is the black viscous umbilical chord that is oil, another reason can be seen by firstly looking at the world banks data on countries military expenditure as a % of their gross domestic product or in leymans terms how much of their total countries wealth production is spent on their military, scrolling down the list you will see one of these is not like the others, in fact Saudi Arabia spends a whopping 9% of its G.D.P. on its military (the U.K. spends 2% as a gauge) when you consider Saudi Arabia's gross domestic product estimate in 2015 will be 805 billion  You can appreciate that is a lot of cap guns. So Saudi Arabia has a lot of oil to sell, some countries in the west would like this oil, coincidentally these very same countries are very good at building weapons of war and as I alluded to earlier Saudi Arabia wants to spend spend spend on weaponry. At this point I imagine someone somewhere in the west muttered the immortal words of balderick "I have a cunning plan, buy the oil from the Saudis and then sell them loads of weapons to recoup some of that cost.......genius"