It depends on your situation, if your single and not having any visitors comming down that your paying for than no you will not spend as much as we did, not even close. However, we spent what we spent; without going into a speadsheet I'll give you some numbers on things we spent.
$2,700 on Nex and Abbotts bills (depends on what you get, but I think you'll be spending right around that.
$300 for the trip down to Florida, that was money that payed for gas, hotel as well eating out everyday (every meal) until OCS started, got down on the Thursday before OCS.
$200 for OCS initially, shoes and powerbars and stuff
$250 Class dues (there is a baseline in class dues, if you have more guests at events that you pay for or want more t-shirts expect to pay more than your counterparts (mine was in the middle of what people spent)
$180 first liberty weekend, got a hotel out in town (after 1st PI, 5th week?), if you secure later you'll spend a lot less (could of stayed at the BOQ, but I wanted to get away from the base)
$460 ($140 for hotel for two days)($35 dress for dinning out)($200 gas and food for her down and back)($125 for food for the both of us (2 breakfasts, 2 lunches, 2 dinners)
$620 when my wife down to visit me the second time ($210 for hotel for three day, memorial weekend)($200 gas and food for her down and back)($210 for food for the both of us (2 breakfasts, 2 lunches, 3 dinners)
$200 for power bars I bought some she bought and sent
$160 on a Nintendo DS and games which made the nights go by better
Thats a little over $5000 spend before Candio phase when you can go out every night and blow money
Would account for rest but to lazy
No money spent on hookers and blow, the wife and the OCR would not allow it.
My best advice to you is if you want to spend the least amount of money possible, be a nasty class (secure later= spend a lot less), be single (concentrate your efforts towards courting some people at Floribama or Seville's, gambling with STD's though), don't order extra t-shirts (your gonna spend $60 dollars Minimum (3 shirts $20 dollars each), so if you have family and they would like a cool souvenir don't do it, get them a post card ($1.00, good deal) Don't drink beer if its not bought for you drink water, lemons should be no charge. Smiles all the way through the bottom
Bottom line your gonna spend more than you think, $300 is fine your have access to your ATM as was said before, and all you have to have is a $20 bill when you check in.