".....The sharing of family wealth has been a critical component in maintaining the semblance of a united front within the royal family. An essential part of family wealth is the Kingdom in its physical entirety, which the Al Saud view as a totally owned family asset. Whether through the co-mingling of personal & state funds from lucrative government positions, huge land allocations, direct allotments of crude oil to sell in the open market, segmental controls in the economy, special preferences for the award of major contracts, outright cash handouts, and astronomical monthly allowances, - all billed to the national exchequer - all told, the financial impact may have exceeded 40% of the Kingdom's annual budget during the reign of King Fahd. Over decades of oil revenue-generated expansion, estimates of royal receipts have varied, ranging as low as an unlikely $50 billion and as high as well over $1 trillion. [5]. This method of wealth distribution has allowed many of the senior princes & princesses to accumulate largely unauditable wealth and, in turn, pay out, in cash or kind, to lesser royals and commoners, and thereby gaining political influence through their own largesse.
During periods of high oil prices as were the late 70s, early 80s, and again, immediately after the 2003 US invasion of Iraq, national income has outpaced the developmental needs & social obligations of the Saudi government and the effects of royal skimming were diminished. From the mid 80s through the 90s, when international crude oil prices dropped to the teens and below, the subsequent shortfall in income, and the availability of surprisingly limited financial reserves (when compared to such countries as Kuwait and the United Arab Emirates which continued to grow during crude price droughts because of dividends generated from years of prudent investments.)[6]. According to well-publicized but unsubstantiated reports, King Abdullah has intentions to reduce the Al Saud share of the budget, an act which may sow discontent within the royal family, but would be popular with the Kingdom's citizenry."
Fact is no one knows really how much the Royal family keep and how much gets shared.
Saudi Arabia has the wealth to never export oil but to process it all on shore. INstead that potential excess to invest in expensive downstream processing goes in to the royal family.
Afghanistan will be the same.
Have a read of :
http://www.amazon.com/Plowing-Sea-Nurturing-Sources-Developing/dp/0875847617