Yes, are you looking for a match, left, right, or outer?
Not to say you are wrong but really? Do you have oil coming out of it in any form of a drip, or is just the sweat/seepage we see in the photo? If you are not loosing oil in significant amounts it's nothing to worry about at this time. As far as case halves go, they do not have to be mated/matched, and I believe, (but not 100% positive) 99 up are the same for the 250 on the main cases. But let me do more research before you go nuts an get one.
What I see is the casting in that photo, is there a crack I am missing? I can usually spot a good crack.
If the break doesn't intersect a bearing socket I always sober Floyd up or give him enough coffee that his eyes are open and just have him weld it.It drips oil when the bike gets hot. I will probably just get someone to aluminum weld