I've only called weddings for good friends, and I do that for free. But I've played a lot of weddings, and I generally would not take a wedding gig unless it paid at least 2-3x what a normal dance would pay.
For a single caller, assuming you're NOT bringing sound or being in charge of the band, you'll probably have some MC duties, at least. It's been that way at pretty much all of the weddings where I've played for a dance. As Alan and Jeff said, it doesn't matter how much time there will be actual dancing; you'll end up being there for quite a while in any event with setup, etc. Keeping your time to a minimum isn't going to be a priority; I've played weddings where the band sets up and finishes sound check literally three hours before going on.
I recommend getting the couple on the phone immediately so you can gauge what they're looking for. Generally, I think about it in terms of how long I need to be there. If it's a local gig, I'd start with something like $150 for the first hour I'd be there, and $50/hr after that, plus travel. But I'd ask for more if I had any duties other than playing (or calling), such as setting up sound, providing recorded music, etc. Typically, you won't be at a wedding for less than three or four hours, at least, so you're looking at $250-500. I live in DC, which is not quite as expensive as NY, so adjust accordingly.
I am generally willing to play or call for dances for community events and other one night stands at a much lower rate. With weddings, though, the couple's paying LOTS of money for stuff that isn't as valuable as the music, and I'm unlikely to move much off the initial ask, unless it's a very close friend, in which case I'd do it for free.
-Dave