OMG! I love this thread! The drama! Will she or won't she ...
Everyone brings up so many great points. I'm sort of with Sarah and others. I don't really like diets or bans. I think they create an artificial environment that's very, very hard to really sustain.
On the one hand, I agree that breaking the ban for Halloween might seem frivolous, but special occasions are what make life fun! If you were buying an Avatar costume, I might say no, you're not really going to get a lot of use out of that. But a fabulous LBD that fills a wardrobe gap? Sounds quite sensible to me. Do you need it? Do we need any clothes other than one pair of pants and one shirt that we can wash every night? What does "I have enough" mean? These are all great questions, but I don't think there is one, definitive answer. Life is fluid.
If I say I'm not going to eat sugar or fat, and then I find myself in Paris (um, it could happen!), you can bet I'm going to eat every single fabulous thing I can find. Live! Enjoy! Who knows when I'll be back in Paris?
Yes, it might seem like a justification. Yes, there might be "ego" involved in wanting to look cute at a party. So what? Who cares? Are we nuns? (Not that there's anything wrong with nuns!) Yes, I'm sure you have something in your closet that you can wear, or something that you can borrow. If you truly can't afford to spend the money, that's another story. Are you a failure if you don't stick with your self-imposed ban? Maybe. Maybe not. Maybe you'll have learned something else more important?
You must do what feels right for you. This is the hard part about being a fantastic writer with a killer blog. You put it all out there for everyone to see, and everyone will have their own opinion. I say life is too short! Sorry - I know I'm no help. Whatever choice you make is the right choice for this moment!