No, it's not your fault they aren't sending you paychecks anymore and have closed, but if you owe the money then you owe the money. You bought the uniforms knowing that you'd owe for them and basically they "fronted" you the money for the uniforms so you didn't have to pay for them all up front and could spread out the payments.

And regardless of whether you voluntarily terminated or the company closed, you are no longer employed. It would be the same thing if you were fired, you would owe the balance out of your last paycheck or be sent to collections. Just because you don't voluntarily quit doesn't mean you just get out of debts.