IronWind Metals now has the old Mongoose Babylon 5: A Call to Arms miniatures available. They are remastering many of them so only the core units are currently available but they say they will have the entire range available again over time. We have not seen any of them yet so we cannot say how well they look.
See the original Mongoose Publishing announcement about dropping the line.
Update: Well now it looks like they are going away again as Mongoose is not renewing the license for Babylon 5. Production will cease at the end of June 2009. See the announcement.