No one can give an exact value here - the reason: It's basically a collector's item since it is outclassed by Jizai. I think at least 90% of the people on this server aren't even remotely interested in getting a Sange & Yasha. I'm pretty sure, though, that some people go crazy over it, and it's those people that will bid high.
Just auction it and see what you can get. anime's guesstimate still sounds too hight to me, but who knows. However, since...
1) Sange isn't an Uber
2) S&Y isn't particularly useful
3) the Mil Lily drop is not extremely hard (of course, the hit makes it rare)
you might get unlucky and receive only low bids. If you're not able to sell it now, just keep it. I'm sure you're going to find a buyer in the future. I also think that if you were to combine it with a Yasha already, you'd be able to sell it more easily.
All in all, though, I don't think this item is as valuable as you might have hoped or thought when you first posted this price check.