I think it is going to vary extremely from country to country. But for the sake of brevity and partly because they are more well known, I'm going to stay with the big three "fascist" countries, that is Germany, Japan, and Italy.

Starting with Germany, its hard to argue that the Nazis only considered war due to economic factors. The Nazis had risen to power with the idea of reclaiming lost German lands and the plan to create living space for the Germans in the East. So with this in mind I don't know that one can claim that economic reasons were the sole or even the main motivation behind Germany's conquests. But economic motivations and factors did play a big (and often under discussed) role. The need for resources to fuel Germany's growth was a huge motivation to invade the Soviet Union. Hitler and the Nazis coveted the Soviet Union's vast reserves of Oil and nearly unlimited food supply (in the form of the Ukraine and other grain rich areas). The Nazis state needed Oil and the other essential raw materials contained in the Soviet Union, so in the case of the Soviet Union ,economic motivations were a big reason for invading.

The German economy had been drained by rearmament, German military increased every year the Nazis were in power; by 1939 German military spending was triple what it was in 1934. In 1938 military spending was nearly 20% of the German GDP. Simply put this type of rapid and vast rearmament is basically impossible to sustain; even with an economic genius like Hjalmar Schacht working miracles.

The Nazis were on the brink of economic collapse, but they were given a temporary boost by the seizure of Austrian and Czecho-Slovakian gold reserves. The German economy can thus be seen as a "War Economy in a state of Peace". It was an economy that basically needed to be in a near constant state of war to function.

Finally, there was one other main economic motivation for Hitler and the Nazis. They wanted Germany to be completely independent in terms of resources and trade. Germany had to import a number of important raw materials and was also forced to import food. Hitler wanted to create a Germany that could produce everything it ever needed. So given all these factors it could definitely be argued that there were significant economic motivations for Germany to go to war.

Japan is in the same boat with a slightly different backstory. Japan was still a rapidly industrializing nation in the 30's. Heavy industry was growing at a rapid pace and Japan needed access to raw materials like iron, steel, oil, etc. Japan's leaders much like the Nazis also wanted to be economically independent and self sufficient in resources. Early on Japan had identified that it would need to seize territory in East Asia to ever become truly independent. Territory in the Dutch East Indies, Malaya, and Borneo held the resources Japan would need to continue her industrialization unhindered. The Oil and Metal embargo placed on the Japanese by the USA essentially forced Japan into a decision; either submit to western demands and give up all their hard won territory in China, or fight the west and achieve economic independence (among other things).

Italy is in a completely different situation than the other two. Where as the other two had clear cut economic motivations for going to war, Italy's ambitions were almost entirely territorial. Italy wasn't sufficient in resources by any means (they had to import most of their coal from Germany) but, as far as I know Italy and Mussolini weren't as concerned with setting themselves up as a completely independent economic state. Italy wasn't close to ready for war in 1940 when they declared war. Italy was very much an opportunist, and wanted to wait until 1942/1943 to pick a side, that was also when Mussolini's generals told him he the Italian Army would be ready for war. However, when France collapsed so rapidly, Mussolini sprang into action, he thought the war would be over in a few months and did not want to lose his seat at the peace table. Italy had wide reaching territorial ambitions and wanted to create a "Greater Italy" that included territory from France, Britain, and other smaller nations, it wanted to set up client states in the Balkans and Spain, and finally it wanted to expand its colonial empire.

Sources:

Wages of Destruction Adam Tooze

The Economics of World War 2 Mark Harrison