They "give" you the uniforms. They then "steal" money equaling the amount that the uniforms cost from your "savings".
You pay for your uniforms recruit. End of story. They are lying if they tell you different.
You'll also pay for ANYTHING you get at the commisary / PX while you are there.
So, when you "get" soap, or a wallet or anything (you DO get visits there while you are at bootcamp), you'll pay for that as well. They do provide basic soaps and stuff, don't get me wrong, but I know some recruits who bought hair care products, etc (shampoo felt GOOD). You'll pay for pictures, dress blues (if you are lucky enough to be the Guide for your platoon), and several other things.
You also get a uniform allowance every year while in the Corps. This is to pay for uniform items that wear and tear. You get this money whether or not you buy new uniforms.
Unless the pay scale has changed a LOT since I retired in April of 2000, Pvt and PFC's do not make $3,000 TAKE home in 13 weeks.
As a PFC I think you get around $800 AFTER taxes (single and 1) and around $600 for Pvt's.
You WILL pay taxes while in the Marine Corps.
You WILL pay for your uniforms and other "personal" items.
I think you even pay for your haircuts.
You will be allowed to stay off some debts because of the Soliders and Sailors Act until you graduate... but a Mortgage is not one (they'll still start foreclosing on the house if the payment isn't made). So you'll have to take care of that before you head out.
So, I would say that if you have your Eagle Scout Award / some college experience, then you probably should have a decent amount of money when you leave... by decent I mean $1500ish.
Last Marine I knew who went through Boot Camp (A PFC I talked to during a Wall Locker Inspectionin December of 1999)came out with a little over $1800 (like $1817 or something like that)... but I don't know their spending habits during BC.
Let me know if you have any more questions. The Marine Corps is a great band of brothers and something few regret joining.
Semper Fidelis