I would sit your kids down and just have a hear to hear discussion.  Tell them you love them, that you want to give them the world, but right now, it's a bit if a difficult time.  Tell them you do your best to make money and to support the family, but that the whole family has to be careful with money together.  Make it sound like it's a sort of family mission.  Tell them that you hope in the future that you can buy them anything and everything they want, but right now you can't buy these expensive things.  Kids are understanding.  They will understand.