I went through this a while ago but I bought my Router from Carving CNC ( Now OMNI, I think ) and I just ordered one directly from them.
Other option would be to get all the specs and look on Aliexpress. I think they are pretty standard.
I assume its a 1605 ballscrew? You need to take measurements of the drive end so it matches what you have.
Would have though t it easier to get one through the original supplier, but maybe not.....we know what they are like.....