I'm not sure if anyone has done this before but I got really sick of the world market constantly offering small countries tons of units so I looked around in the gmc files and found that if you delete whatever is in the armsavail: section the world market offers will drop considerably. They still offer the occasional supply truck but I find the game to be MUCH more enjoyable. Without the constant supply of units AI countries economies actually do much better too.
Just open up the scenario folder and open a gmc file(i used notepad++)(please backup your files as well, I've played a few campaigns without any problems but you never know). each nation has an arms available line and a letter for the types of units the world market offers. just delete those letters and the world market no longer offers those units to that country, simple as that.
BUt how do you think arms dealers benefit? Aggravating smaller countries, that is