The initial entry fee of ~$2,500 has been waived for the incoming class. As noted, mids will still pay it, but will do so as part of their initial interest-free loan. Mids pay for uniforms, books, football tickets, laundry and dry cleaning, and many other items out of their pay. Much of it is (or, at least was) automatically deducted, and mids have virtually no choice in terms of what it costs.
There are some options for the cost conscious (or, at least, there were). For example, you could opt to purchase at least some uniforms that were previously owned. And, you can always reduce "optional" expenses, such as Midstore purchases, eating in Steerage, etc. In my day, your class ring (up to a certain dollar amount, as I recall) could be taken from your USNA account and choices are involved there in terms of stones, gold, etc.
Mids get a fixed amount of "spending money" each month, based on their seniority. Many mids live on this and some even send money home. Others get help from their parents, friends, etc. Trips home are on your own. And, sad to say, some mids cannot afford to go home other than perhaps for Christmas break.
Whatever funds from your USNA account that you don't spend over the course of four years, you get/got as a lump sum upon graduation. In my day (a LONG time ago), men typically got around $5,000 and women about half of that.
NOT, BTW, for the reason you probably think. Women had to (and may still have to) purchase skirts in addition to pants, extra shoes (heels to wear with the skirts), purses, etc. Also, because there were so few women, uniform items were always more expensive. In my day, for example, women's covers cost $60 whereas men's were about $25. Also, the small number of women meant not as many options in terms of buying used clothing. Not complaining -- that's just the way it was.
Obviously, many things have changed. The fact is that mids can survive (and some do) on the money you get while a mid. However, I would guess that the overwhelming majority of mids get at least some financial help from parents or other relatives -- primarily in terms of trips home, etc.