How much the world spend on drugs ?

It was estimated in the year 2000 to be around four hundred billion U.S. dollars.

The crazy thing about this is that the afghanistan peasant or Colombian peasant who grow the coca leaf or poppy flower are paid a few dollars for stuff which is traded in big u.s cities for hundreds of thousands of dollars.

 look for it here

he could be using some budgeting software such as http://justbudget.com and see by himself. but i think it really depends on individuals and what drugs they are using.

 not only regarding drugs but anything, some people are more into gadgets than others. and some people are more creative then others. so you are gonna see people buying lost of pipe and not always use them. and other people not buying any but making them themself. which saves a lot of money. that is about the material.

 then you got the expenses that goes with where you are taking the drug. movie theather, etc.

 and the drug itself, marijuana, meth and cocaine does not lead to the same budget numbers.

oh, sorry, I just realize you are asking about how much the total drug market is worth. oh my god. this will always be a lot more than any estimates.

 especially if you include prostitutions that pays out for a lot of "free" drugs handed to the girls. and you might want to include some money from the weapon market as well and it is necessary as well because its illegal.