Party bags are a tricky subject, no matter the time of year or occasion. Although bag lovers are generally not super price-sensitive (by definition, you can't really be in the market for a $2,000 accessory and be accurately described as "price-sensitive"), everyone likes to feel like they're getting a good value, and special occasion bags are just that--for special occasions.
Most of us end up buying a party bag sooner or later, though, and right now is the perfect time of year to do it--not only are there plenty of available options that will be useful for years to come, but any party bag you buy at the moment will probably get taken out for at least a few spins before the first of the year, so it'll feel less like something you bought and immediately put on a shelf in your closet. And then, every time you take it out in the future, you'll be glad you're prepared.
Naturally, we have some suggestions. (We always have suggestions.)