How the Nazi's win matters. I am assuming Moscow falls in 1941, and the USSR is out of the war by 1942. Both the USA and UK remain hostile and undefeated, but they both make a cold peace with Germany.
The German military continues to consume a high level of resources and the budget. For the 100 million or so Aryans, the standard of living will be above prewar levels. For the elite of the German Reich, the lifestyle will simply be lavish.
Food will be an issue at list initially and there will be famines both cause by bad harvests and intentionally created to starve Slavs. For example, the SS may simply remove any "Aryans" from Leningrad and Moscow, form a perimeter around the cities, and simply starve all the population to death over a year or so. The famines will be more severe than Lenin/Stalin's but will be focused on Slavic areas.
Germany planned to create the "ideal" farming communities, where the Germans are the overlords, and the Slavs are the slaves. The ratio will be about 1 Aryan for every 10 slaves. Treatment of the slaves will be between old time western hemisphere slavery and "extermination through labor" camps. The farms will produce a surplus, but will be wildly inefficient base on any labor or land measure. The Germans tried to setup one of these ideal communities in OTL. All the local Poles had left (majority) or had weapons (partisans, small minority). The Slavs will flee the German area, especially in 1941 to 1943. These fleeing Slavs will be one of the largest migrations in human history. Hitler will continues to run the death camps to at least kill all the Jews and likely continues to run the camp to kill some percentage of the Slavs. At least in some of the planning documents, it was 1/3 of the Slavs killed, 1/3 slaves, 1/3 moved outside of Reich. This probably gives a good ballpark with 100% of the Jews killed, and 66% reduction in Slavic population. This depopulation will be larger than the Black Death, but less severe than what happened after Columbus. Much of Eastern Europe will convert to wilderness or wildlands like the Chernobyl zone or the New World after disease had killed a majority of the natives. The German will likely move enough Slavs from farther east to keep Poland, the Baltic,and the most fertile areas of the Ukraine populated. Likewise the Germans will have industrial cities at mines and other resource areas such as the tungsten mines of the Ukraine. In large parts of Belarus and Russia proper, the population decline will be over 90%, and for all effective purpose, there will be no economic activity. This will be especially true in the colder north of Russia and on poorer/dryer soils.
To summarize, it will be much like any slave/serf economy. It will be poor if you look at the entire population, but it will be rich if you look at only the Slave owners and the average resource per Slaver.