zebra, check for Dressed for Success in your area, too. They take donations of work clothes for women re-entering the workforce.
nertsmommy - welcome. I'm sorry to hear things are so tight for you right now, but it sounds like there is an end in sight with the kids coming back to you in January. My son asks about coupons, too, haha. I try to avoid saying we can't afford things, but say, "we're not choosing to spend our money on that" and explain why. Like, we have money to pay for a warm house and healthy food and shoes and clothes, or we could buy some junk food that won't help us grow and toys. Which is a better use of our money? He's 4, but he's starting to get it.
I also have a list in my purse, and anytime he sees something he likes, he asks me to write it on his list. He rarely asks for any new toys when we're out, but he frequently asks me to write it down. He knows that some of the toys that he likes at the store will show up at our house if I write them down - thank you Craigslist and Freecycle - so he's been amenable to the idea. It has saved a lot of whining at the store.