I sympathize with you. I never want to go to those things, either.
If the sweater is dressy, you can pair it with a black skirt and a pair of pumps or slingbacks. This is how I would think in a pinch like this:
I would first run to the Goodwill and try to snag a satin-y black skirt and then to Target for the shoes and a pair of black pantyhose. If Goodwill didn't have a skirt, then I would look for one while at the Target and then run to Ross if I had to. I've never been in a situation in which these three stores were not able to save my ass. And since we have these stores in common and all...
I'm not one to be a real stickler about clothes for an event that I really don't want to go to, though. As long as I've got something wearable and suitable, I'm happy. You might have a whole different take on it.