Cadet pay is complicated.
I'm sure they actually do pay us ~$900/month (35% of an 0-1's pay is $989), but that is not what we see in our bank accounts on pay day.
Plebes will have $225 direct deposited in their personal bank accounts every month, and yuks have $305/month. I'm not sure about what cows and firsties get 'cause I'm not there yet. However, my understanding is that by law, they have to pay everyone from plebes to firsties the same amount. The way that they can still say "the amount increases each year" is that they deposit more of the $900-whatever dollars we earn in our personal checking accounts.
Ah! But where does the rest of the $900 go? Excellent question. The rest of the pay is deposited in the ever-mysterious "cadet account" that every cadet has. The amount per month changes just about every month. This is probably because every New Cadet is given a sizable pay advance to cover the large amount of items they are issued during Beast. From this account, frustrating and undefined expenses like the "DCA Cadet Activities Fee", "Army Athletic Association Fee", and recurring "Personal Services" fee (haircuts, even for females who don't get 'em from the cadet barbers) and "Laundry & Dry Cleaning" fee (even if you don't use the optional laundry service) are deducted.
A week or two into yuk year, cadets are allowed to access the cadet account after expenses have been deducted (a pretty large amount, actually) for the first time and take out a certain amount of the extra money in there (called "top off"). They cannot take everything out, however. There is a minimum account balance (MAB) set for the account that you cannot withdraw past. The treasurer changes the MAB periodically for each class based on projected expenses for that particular month or year.
So, basically, even cadets aren't really sure how the pay breaks down.
Here's a link which could be helpful for you, though:
http://www.usma.edu/dcomm/club/2014_expenses_summary.pdf
Also, I have no idea what this alleged "shoe repair" service is.