I know the obvious answer is to get the snare to not buzz but before it gets tracked
I think you answered your own question here.
When an instrument is tracked, you are doing little more than converting sound waves to electricity. There is no magic plugin or trick to make a snare drum sound like a frog, a chainsaw, or an opera singer. When you want to change the fundamental character of an instrument, you may as well want to change it into a frog or chainsaw.
So, I'd learn from this and make sure that you ALWAYS get what you are looking for when tracking. This is how the big boys do it.
Now if you really have to change the snare out, you have a few options.
1) You can go the fake route and gate the crap out of it. I've had good luck with the Waves C1 gate for this, but there are others that would do a ton of good as well. So much of this technique depends on the snare, the drummer, how it was recorded, the room it was recorded, and the song so I'm kind of guiding in the dark here.
2) You can go the fake route and use a sample. This is probably the "least fake" of all your options. Of course, the overheads will still have that buzz or ring in there and who knows what that will sound like.
3) Retrack the drums. No offense, but it sounds as if someone failed. I'm going to go ahead and blame you because every person who hears a recording with your name on it is going to blame you 100%. It's your fault. You didn't force the drummer to tune his snare properly. You didn't give him a few different snares to work with. You could have prevented this at the source and saved a ton of time talking on this forum, for example. (I don't mean to be a jerk. I've had to learn these lessons the hard way and being firm is the only way anyone else will learn..)
Brandon